If radiolabeled carbons are introduced into the citric acid cycle, what happens to them across multiple cycles?

• A. Only half of the labeled carbons are released in the first cycle, and the amount decreases by half in subsequent cycles.
• B. Labeled carbons are never released.
• C. All labeled carbons are released in the first cycle.
• D. Labeled carbons double in number each cycle.

Answer: (A)