A Mismatch occurs when: A. organisms that were well adapted to one environment cannot evolve rapidly enough to adapt to new circumstances.
B. when an organism is well adapted to its environment
C. when an organism inherits a mutation that decreases its reproductive success
D. when a mutation increases the reproductive success of an organism

A

Explanation:

A mismatch occurs when organisms that were well adapted to one environment cannot evolve rapidly enough to adapt to new changes in the environment. Hence, a trait that once confers an adaptive advantage becomes inimical due to the changes in the environment.

In order words, a mismatch occurs when a once adaptive trait becomes maladaptive or no longer confers an adaptive advantage to organisms due to a change in the environment but still persists in organisms.

For example, an organism with a body adapted to aquatic habitat suddenly finds itself in a terrestrial habitat due to climate change. The body that use to be adaptive to the environment would suddenly become maladaptive to the new environment.

The correct option is, therefore, A.