A protein that contains all the essential amino acids in the proper proportions is called:
Correct Answer: C
Rationale: A complete protein is the term used to describe a protein that contains all the essential amino acids required by the body in the right proportions. This makes choice C the correct answer. Choice A, 'simple,' is incorrect as it does not reflect the concept of essential amino acids. Choice B, 'indispensable,' while related to importance, does not specifically address the presence of all essential amino acids. Choice D, 'complementary,' is also incorrect as it refers to combining proteins to achieve a complete amino acid profile, rather than describing a protein that already contains all essential amino acids.