Final answer:
To make a glycerophospholipid, fatty acids are esterified at the 1st and 2nd carbons of the glycerol backbone, making A. the correct answer. These molecules form the basis of cell membranes with a typical structure including a saturated and an unsaturated fatty acid.
Step-by-step explanation:
To make a glycerophospholipid, fatty acids are esterified at the positions on the glycerol molecule. Specifically, the fatty acids are bonded through ester linkages to the first and second carbons of the glycerol backbone. Therefore, the correct answer to the question is A. 1st and 2nd carbons. Glycerophospholipids are a major component of cell membranes, featuring two hydrophobic tails from fatty acids and a polar head composed of a phosphate group. The typical structure includes a saturated fatty acid at the first position and often an unsaturated fatty acid at the second position of the glycerol moiety. The third carbon of the glycerol is usually linked to a phosphate group, which may be further esterified with another alcohol, such as choline or ethanolamine, forming different classes of glycerophospholipids such as phosphatidylcholines or phosphatidylethanolamines.