Final answer:
The functional group that involves fatty acids and amino acids is the carboxyl group (option a). Carboxyl groups are found in amino acids and fatty acids and make the parent molecule hydrophilic by releasing hydrogen ions (H+).
Step-by-step explanation:
The functional group that involves fatty acids and amino acids is the carboxyl group (option a).
Carboxyl groups are found in amino acids and fatty acids.
They release hydrogen ions (H+) from the COOH group, making the parent molecule hydrophilic.
Other functional groups, such as the carbonyl group, also contribute to the hydrophilic nature of molecules.