Nutritious Substance for Building Muscles
Puzzle 10 of Words with Pros and Cons Pack
Question is: Nutritious Substance for Building Muscles
and the answer is: PROTEIN
Word Meaning:
PROTEIN — (biochemistry, countable) Any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds.
Definitions from Wiktionary.