A phospholipid has two fatty acid tails, which consist of hydrocarbons with even numbers of carbons ranging from 4 to 28, and a phosphate group attached to a glycerol head, which is hydrophilic. Monoglycerides contain only one fatty acid chain bound to a glycerol head, and triglycerides contain three fatty acid chains. 

A fat (triglyceride/triacylglycerol) consists of three fatty acids linked to glycerol. A phospholipid consists of two fatty acids and a phosphate group linked to glycerol. Thus removing a fatty acid from a triglyceride and replacing it with a phosphate group will yield a phospholipid. Diglycerides contain similar structures to triglycerides, but only have two fatty acid chains bound to the glycerol head. Steroids are lipids, but do not contain fatty acids. Rather they contain four hydrocarbon rings, and they are all derived from cholesterol. The saturation of a fatty acid refers to the presence of hydrogens anywhere they can potentially be present. A saturated fatty acid is said to be saturated with hydrogens.

The tails of phospholipids consist of hydrocarbons only. Thus they are nonpolar, hydrophobic, lipophilic and fat-soluble.  

The tails of phospholipids are hydrocarbons and are thus hydrophobic so they point towards the interior of the membrane to avoid contact with the aqueous solutions of the cytoplasm and the extracellular fluid.  

Cholesterol is class of lipids known as steroids. All steroids have four fused carbon rings in their structures. Fats, fatty acids and phospholipid do not contain any ring structures. Fatty acids are components of both fats and phospholipids and are long chains of hydrocarbons. Phospholipids contain two fatty acids attached to a polar head and a phosphate group.

The heads of phospholipids are hydrophilic and so they will face the exterior of the cell membrane in order to interact with the aqueous environments of the extracellular fluid and the cytosol. The hydrophobic tails will face the interior of the membrane to avoid water contact.

Lipids are mostly made up of hydrocarbons, which makes them nonpolar and thus, hydrophobic. Glycogen is a type of carbohydrate; it is the storage form of glucose in animals. Amino acids are the monomeric units of polypeptides.  

Because lipids are made mostly of hydrocarbons, they are nonpolar and thus hydrophobic, which means they avoid contact with water. The root "hydro" refers to water and the root "phobic" refers to fear. Hence hydrophobic means "water fearing". Hydrophilic on the other hand means "water loving" and is used to describe polar molecules.    

Glycogen is a carbohydrate. It is a polysaccharide that animals use to store glucose when sugars are needed by the body for fuel. All other answer choices are lipids.

Monosaccharides such as fructose are carbohydrates not lipids. Waxes, steroid hormones such as testosterone, estrogen and progesterone, and triglycerides (fats) are composed mainly of hydrocarbons and are classified as lipids.