Final answer:
Phosphate groups exclusively participate in hydrophilic interactions.
Step-by-step explanation:
Among the given options, the group that participates exclusively in hydrophilic interactions is option c, phosphate groups; hydrophilic. Phosphate groups have a negative charge and can form hydrogen bonds with water molecules, making them hydrophilic. Hydrophilic functional groups are attracted to water due to their polarity or charge characteristics. In contrast, hydrophobic groups repel water.