What is a complete protein, and name two good sources.

• A. A complete protein contains all nine essential amino acids; eggs and dairy are good sources.
• B. A complete protein lacks one essential amino acid.
• C. A complete protein is only plant-based.
• D. A complete protein has been heat-treated.

Answer: (A)

A complete protein provides all nine essential amino acids in amounts adequate for the body's needs, and eggs and dairy are classic examples because they deliver all nine in good balance and are highly digestible. This combination makes them high-quality protein sources that support growth and maintenance.

Why the other ideas don’t fit: a complete protein does not lack an essential amino acid—it would be incomplete. Saying it’s only plant-based is incorrect because animal products are also complete; while some plants can be complete, the blanket statement isn’t true. Heat treatment does not determine completeness; cooking can affect digestibility but not the presence of all essential amino acids.