Fruits evolved primarily as structures specialized to fruits evolved primarily as structures specialized to
- protect pollen
- provide a source of food to the plant's embryo
- disperse seeds
- provide food for humans
- protect seeds

Option C. "disperse seeds"

Explanation:

Fruits are evolved from the dispersion of seeds which are formed from ovules  present in the ovary.

Seed dispersal can be defined as the movement or transfer of seeds away from the parent plant.

There are several ways of seed dispersal that supports evolution of fruit including by animals, birds , insects, wind and water. Animals went to plants for the purpose or food and some seed get stick to their body which helps in seed dispersal to other places, Birds and insects get attracted to the appearance of flowers and carry seeds or some pollen with them and spread on other flowers, wind transport seed along with it and plants near a river or water surface uses the flowing water to transport their seeds.

Hence, the primary structure responsible for fruit is disperse seed.

i'd have to say the answer is probable the second option "the geosphere interacting with the atmosphere"