Which statement is true of essential amino acids?

• A. They can be synthesized by the human body in sufficient quantities.
• B. They are stored in the body for long-term use.
• C. They are only required during periods of rapid growth.
• D. They cannot be synthesized by the human body and must be obtained from the diet.

Answer: (D)

Verified step by step guidance

1. Understand the definition of essential amino acids: Essential amino acids are those that cannot be synthesized by the human body in sufficient quantities and must be obtained through the diet.
2. Evaluate the first statement: 'They can be synthesized by the human body in sufficient quantities.' This is incorrect because essential amino acids cannot be synthesized by the body.
3. Evaluate the second statement: 'They are stored in the body for long-term use.' This is incorrect because amino acids are not stored in the body like fats or carbohydrates.
4. Evaluate the third statement: 'They are only required during periods of rapid growth.' This is incorrect because essential amino acids are required at all times, not just during growth periods.
5. Conclude with the correct statement: 'They cannot be synthesized by the human body and must be obtained from the diet.' This accurately describes essential amino acids.