Final answer:
The group capable of only hydrophobic interactions is d. fatty acid groups; hydrophobic because they are nonpolar and aggregate away from polar water molecules resulting in hydrophobic interactions.
Step-by-step explanation:
To determine the group capable of only hydrophobic interactions, we must look at the properties of each group.
- Phosphate groups are hydrophilic, as they can form hydrogen bonds with water due to the presence of a negative charge.
- Fatty acid groups are long hydrocarbon chains that are hydrophobic because they lack the ability to form hydrogen bonds with water, as they are mostly nonpolar.
Therefore, the correct answer is d. fatty acid groups; hydrophobic.
These groups interact through London dispersion forces, which are the weakest form of van der Waals interaction that occurs between molecules.
The nonpolar character of fatty acids causes them to aggregate away from water, driving the formation of hydrophobic interactions.