Whenever we have a comparison, we want to make sure that the two things we are comparing are parallel.
Here our sentence gives us the number of olfactory receptors in "the nerve lining of a mouse's nose". So we want to compare it to the number of olfactory receptors in the nerve lining of a human's nose.
A. In an exhaustive study that explains how humans distinguish different scents, Dr. Linda Quidd asserts that the nerve lining of a mouse's nose contains roughly the same number of olfactory receptors that a human nose does.
We can't compare the nerve lining of a nose to ... a complete nose. We want to compare nerve lining to nerve lining. Eliminate.
B. In an exhaustive study that explains how humans distinguish different scents, Dr. Linda Quidd asserts that the nerve lining of a mouse's nose contains roughly the same number of olfactory receptors that human noses do. Again, we can't compare the nerve lining of a nose to complete noses, plural or singular. Eliminate.
C. In an exhaustive study that explains how humans distinguish different scents, Dr. Linda Quidd asserts that the nerve lining of a mouse's nose contains roughly the same number of olfactory receptors as that of a human nose.
Here, "that" stands in for "nerve lining", so our sentence compares the nerve lining of a mouse's nose to the nerve lining of a human nose. This is parallel!
D. In an exhaustive study that explains how humans distinguish different scents, Dr. Linda Quidd asserts that the nerve lining of a mouse's nose contains roughly the same number of olfactory receptors that those of a human.
Two problems here: 1) "Those" is plural", so it can't refer to nerve lining. 2) We want to have the nerve lining of a human nose, not the nerve lining of a whole human body. Eliminate.
E. In an exhaustive study that explains how humans distinguish different scents, Dr. Linda Quidd asserts that the nerve lining of a mouse's nose contains roughly the same number of olfactory receptors that human noses.
Again, we're comparing nerving lining to noses - not parallel. Eliminate.
