TOEFL Reading: ETS-TOEFL阅读机经 - 43CADX78U1FP7FCSL$

Paragraph 3 supports which of the following ideas about amino acids A. Amino acids are not produced by the human body and must be obtained from food. B. Certain amino acids that people need for building and maintaining body tissue cannot be acquired from plant proteins. C. When legumes or cereals are consumed alone, they do not provide all of the essential amino acids. D. Legumes are missing many more of the eight essential amino acids than cereals are.