Question

which phrase best completes the sentence?
isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine are also known as?
4 important pairs
essential amino acids
synergistic amino acids
complimentary amino acids

Explanation:

Isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine are among the essential amino acids (the body cannot synthesize them and they must be obtained from diet). The other options don't fit: "4 important pairs" is incorrect (there are 8 listed here, not 4 pairs), "synergistic amino acids" and "complimentary amino acids" are not standard terms for this group.

Answer:

B. essential amino acids (assuming the options are labeled as A. 4 important pairs, B. essential amino acids, C. synergistic amino acids, D. complimentary amino acids; if the original option labels differ, adjust accordingly to match the correct option text)