Like all flowering plants, the snapdragon must be pollinated to reproduce, but its flowers are closed. A bumblebee has just enough weight to open a snapdragon flower by landing on it. This adaptation is an example of:

This adaptation is an example of coevolution.

Explanation:

The occurrence of coevolution happens when two or more organisms influence each other's evolution reciprocally via the natural selection method in biological sciences. The expression is often used for two traits, as well as gene-culture coevolution, in the same species influencing each other's evolution.

It is a crucial point of connection among evolution and ecology, in that it is important to consider humans themselves as an essential part of the ecosystem that exerts selective pressure on all species. The prime instances include predator-prey, host-parasite, other inter species competitive relationships, coevolution of flowering plants and their pollinators like bees, birds and other types of insects.

the answer to your question is:

c. complementary base-pairing