T lymphocytes are so titled because they mature in the thymus, unlike B lymphocytes, which mature in the bone marrow. The thymus is located in the anterior superior mediastinum, ventral to the heart and dorsal to the sternum. It is most active in the neonatal and pre-adolescent periods, afterwards, it degenerates and is replaced with adipose tissue. 

Lymphoid progenitor cells are produced in all of the following tissues: the liver, the bone marrow, spleen, and gut associated lymphoid tissue (mainly found in the liver and intestines). However, note that the vast majority of all blood cells are produced in the red bone marrow of long bones by hematopoietic stem cells. 

While all of the cells listed may have some indirect involvement in the overall response to a parasitic infection, eosinophils are the only immune cells that are specialized to respond to multicellular parasites, especially helminths such as hookworms and pinworms. 

Mast cells are rich in granules that contain high concentrations of heparin, histamine, and trypsin, among other preformed proteases. These granules also contain serotonin and various eicosanoids. The function of mast cells is primarily to regulate immune (inflammatory) responses to allergens.

Macrophages, the main blood cells responsible for phagocytosis of debris, bacteria, and virally infected cells, are part of the nonspecific immune response. While they are able to recognize self versus non-self proteins, they are not uniquely sensitive to any particular non-self protein type. Rathe, they phagocytose foreign matter as well as cellular debris. Plasma cells, memory cells, and CD8 T cells are all lymphocytes, and as such they are all part of the adaptive or "specific" immune system, meaning that they are uniquely sensitive to particular pathogenic proteins.

While all of the enzymes listed are present in saliva, lysozyme is the only enzyme listed that has antibacterial properties. This enzyme, present not only in saliva but also in tears, sweat, and breast milk, damages bacterial cell walls, making it an important part of the innate immune system. Amylase breaks down carbohydrates, lipase breaks down lipids, and kallikrein breaks down proteins.

The correct answer is "CD4 T-cells." 

In AIDS, which is the most progressed stage of HIV, the cell type that is most significantly diminished is CD4 T-cells. Often times, the degree of disease progress of HIV and AIDS is established by monitoring the patient's CD4 T-cell count across the course of the illness. The CD4 count guides differential diagnoses when patients with HIV or AIDS present with various complaints, and also guides what prophylactic measures (e.g. antibiotics, antifungals) are administered to these patients. 

While CD8 T-cell, monocyte, platelet, and neutrophil counts may each be decreased for various reasons in patients with HIV and AIDS, the most substantial association between diminished cell count and HIV/AIDS is that of CD4 T-cells.

There are five lobes total in the human lungs: the right lung has three lobes (the upper lobe, the middle lobe, and the lower lobe) while the left lung has two lobes (the upper lobe and the lower lobe).

The topmost part of the lungs is the apex. This area extends into the neck above the 1st rib and is the location auscultated for a diagnosis of a pancost tumor. The lingula of the lung is a small flap of the lowest part of the upper lobe of the left lung. The hilum is the entry point of the lung for the bronchi, pulmonary artery and vein, and nerves. The trachea is not a part of the lung at all; it is the cartilaginous tube that connects the pharynx and larynx to the lung.

The largest airway structure is the trachea. This branches into two smaller bronchi, which enter the left and right lung and bifurcate further into smaller bronchioles. The bronchioles give way into the smallest structures of the lung, the tiny grape-like clusters of alveoli.