What is an evolutionary adaptation of an existing structure for a completely new purpose (e.g., feathers for insulation or for flight) ?

A) exaptation
B) key innovation
C) coevolution
D) adaptive radiation
E) microevolution

Exaptation

A trait that becomes used for an entirely new purpose during evolution.

Key Innovation

An evolutionary adaptation that gives its bearer the opportunity to exploit a particular environment more efficiently or in a new way.

Adaptive Radiation

An evolutionary process in which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available or opens new niches.