Answer:
The correct answer will be co-adaptation.
Explanation:
Co-adaptation is a mutual adaptation of two or more species, their genes, traits and organs as a pair of a group. It happens due to the same selective pressure on both the species undergoing natural selection together.
The case of hummingbirds and flower is such an example in which hummingbirds adapted to have different shapes of the beaks to drink nectar and flowers evolved to produce tasty nectar for hummingbirds.
Thus, co-adaptation is the correct answer.
