Final answer:
Succinate dehydrogenase is the enzyme in the TCA cycle that uses an FAD cofactor to catalyze the conversion of succinate to fumarate. Therefore, the correct option is D.
Step-by-step explanation:
The enzyme in the TCA cycle that contains an FAD cofactor is succinate dehydrogenase. This enzyme catalyzes the conversion of succinate to fumarate. Unlike other enzymes in the cycle that use NAD+ as an electron acceptor, succinate dehydrogenase utilizes FAD. It is integral to both the TCA cycle and the electron transport chain, being the only enzyme that is located within the inner mitochondrial membrane. During this reaction, FAD is reduced to FADH2, which then donates electrons to the electron transport chain, ultimately contributing to ATP production.