D. Polarity and size.
<span>The size, polarity, and charge of a substance will determine whether or not the substance can cross the cell membrane by diffusion. The cholesterol was an example of a lipid, and is highly soluble in the nonpolar environment of the lipid bilayer. You saw, in the animation above, the cholesterol freely passing into the hydrophobic environment of the membrane. Cholesterol distributes freely in the membrane and then some fraction will dissolve in the aqueous environment of the cytoplasm. Water, on the other hand, while polar, is small enough to cross the membrane at a slow rate. Note that specialized transport proteins in certain cell membranes can provide a channel for the water, greatly increasing its rate of crossing the membrane. The lipid bilayer is much less permeable to the ion, because of its charge and larger size. As a general rule, charged molecules are much less permeable to the lipid bilayer.</span>
<span>The person who has a small intestine that has fewer villi than normal would most likely be u</span>nderweight. The villi of the small intestines are the small structures that do the absorbing of the nutrients. Having less of these structures, less nutrients are absorbed and the person is more likely to be malnourished.
More variation assists with survival. It increases the chance that at least some offspring of a parent survive.
Your body type has no indication of your personality. So the answer would be body type.
