Which of the following lipids do not contain a glycerol backbone?
a. sterols
b. phospholipids
c. triglycerides
d. monoglycerides

The answer among the choices is letter A. Sterols is a lipid that doesn't contain a glycerol backbone because it is mostly unsaturated. It can be commonly found on fungi, plants, and animals as an important organic molecule. I hope my answer helps you.

Your answer is  d.)relationship between pressure and air volume and led to the understanding of how respiration works