When sister chromatids are still connected, they are only considered one chromosome. As soon as they separate, however, each sister chromatid is considered a chromosome.

Two chromatids in one chromosome: (X)

Two separated chromatids: (/\)

Because the question states immediately after the sister chromatids have separated, our yeast cells would have 24 chromosomes within the mitotic cell. Once mitosis is completed, each daughter cell would have 12 chromosomes. The question refers to a unique period during which all replicated genetic material is present within a single cell, but separated into fragments that constitute 24 total chromosomes.

Remember that the nuclear membrane is disassembled during prophase of mitosis. It remains absent through the duration of mitosis until it begins to reassemble during telophase. The nuclear membrane is thus absent during prophase, metaphase, and telophase.

The nuclear membrane is present (and essential) during all periods of interphase. The main functions of interphase are the synthesis of cellular proteins, DNA replication, and cellular growth. These processes require proper housing of the DNA and transport of mRNA across the nuclear membrane.

Remember that a cell is defined as diploid if it possesses pairs of homologous chromosomes. During mitosis the cell always possesses homologous chromosomes. The segregation of chromosomes only involves the separation of sister chromatids to opposite sides of the cell, not the homologous chromosomes. The two daughter cells produced contain the same homologous pairs of chromosomes as the parent cell. A cell is therefore always diploid during mitosis and cytokinesis.

A cell will only become haploid during meiosis, when homologous chromosomes are separated during meiosis I and sister chromatids are separated during meiosis II.

A chromosome carries the genetic material for a certain segment of the genome. A chromosome can consist of either one or two chromatids.

During metaphase, there are 46 chromosomes composed of two sister chromatids each that align at the metaphase plate. Then, during anaphase, these chromatids are separated and pulled to opposite poles of the cell. This separation results in 92 separate chromatids in the cell, which are considered 92 chromosomes.

Only germ cells will have 23 chromosomes. These haploid cells result from meiosis, rather than mitosis.

During telophase the chromosomes have been sufficiently separated, and new nuclei can be formed. Telophase functions to prepare the cell for cytokinesis be sealing the chromosomes off from the cytoplasm in a new nuclear envelope.

The nuclear envelope first dissolves during prophase, allowing the chromosomes to migrate into the cytoplasm. They align at the center of the cell during metaphase. Sister chromatids are separated during anaphase, and the cell prepares for the final stages of division during telophase.

During metaphase, chromosomes line up along the center of the cell. At this point, each chromosome contains two sister chromatids.

During anaphase, sister chromatids are separated but remain within the same cell cytoplasm.

A chromosome can consist of either one or two chromatid. A single chromatid is considered a chromosome once it has been separated from its pair. During anaphase, each of the cell's 46 chromosomes is split into singular chromatids, and each chromatid is considered a separate chromosome structure for a total of 92 chromosomes. Once the cell completes division, these chromatids are sequestered into separate nuclei and the cell returns to its normal diploid state.

During mitosis we do not see separation of the homologous chromosomes. This is the reason that meiosis results in a reduction of ploidy and that mitosis does not. Separation of homologous chromosomes occurs after the formation of tetrads, during anaphase I of meiosis.

All of the other answers are processes that occur during both meiosis and mitosis. Both divisions require the condensation of chromosomes and eventual cytokinesis to produce daughter cells. Sister chromatids are separated during anaphase of mitosis, and during anaphase II of meiosis.

Anaphase is primarily characterized by the separation of the sister chromatids. This process occurs by degrading the protein securin, which binds the chromatids together. By degrading this protein, anaphase physically allows the sister chromatids to separate. Immediately after separation, the sister chromatids begin to migrate towards opposite ends of the spindle. Chromosome condensation occurs during prophase, not anaphase. 

Metaphase is the stage of mitosis when chromosomes line up along the equatorial plate, so that they may be accurately segregated into two unique cells. Metaphase is the second phase of mitosis, following prophase.

During prophase, chromosomes condense and exit the nuclear envelope to align during metaphase. Anaphase follows metaphase, and is characterized by the separation of sister chromatids. Telophase is the final mitotic stage, during which the cell prepares for cytokinesis.

Cytokinesis begins shortly after anaphase, when a contractile ring assembles near the equator of the cell. A cleavage furrow is formed and eventually, cytokinesis is completed. Actin filaments are capable of contraction, while tubulin polymers (microtubules) are generally used for cell structure. Microtubules form the spindle fibers used to separate sister chromatids during anaphase, but do not play a significant role in cytokinesis.