Which describes fat? A: a carbohydrate that produces energy

B: a nucleic acid that directs cell function

C: a lipid that stores energy

D: a protein that speeds up a chemical reaction

The correct answer is (C), this is because (A) talks about producing energy as of where fat is a form of storing energy. (B) is talking about a cell that controls its surroundings which, as we know, is not the job of fat. That leaves (D) to rule out as it is a textbook definition of an enzyme.