which part of the amino acid most likely contributes to the hydrophobic behavior if this region in the polypeptide

This question is incomplete

Explanation:

This question is incomplete, however, the side chain is usually the part of an amino acid that is either hydrophilic or hydrophobic in nature. When the side chain has little or no polarity (i.e they lack the ability to interact with highly polar water molecules), the amino acid exhibits hydrophobic properties. Hydrophobic (water-fearing) substances are substances that do not interact/dissolve in water.

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."