Here's a problem to solve: Leucine is one of the amino acids your body needs but cannot make. Which of these happens so that the human body can obtain leucine?

Among the 4 following options, which is the correct answer?

- A: The body converts other amino acids to leucine.
 
- B: The body stores carbohydrates containing leucine.
 
- C: The body breaks down fatty acids to obtain leucine.
 
- D: The body digests protein in food to obtain leucine.
 