Answer :
The flowers and moths coevolved, so that spur-length and tongue-length each evolved because of changes in the other.
Option D
Explanation:
The coevolution is a phenomenon where two organisms that are directly dependent on each other by means of food, or shelter, or both evolve simultaneously keeping the characters complementary so that their relationship doesn't get hampered.
Here in this question the moth and the flower is seen. As the length of the spur increased in flower, the moths with short spur couldn't have the nectar with their short tongue and couldn't survive. So the moths with long tongue survived and hence the co evolution continued.
