Option 1 -> "Invert" means to turn upside down or reverse, which doesn't relate to environmental changes.
Option 2 -> "Accept" means to receive or acknowledge, but doesn't convey the active process of biological adjustment.
Option 3 -> "Adapt" means to adjust or modify characteristics to suit new conditions, the key concept in evolutionary biology.
Option 4 -> "Avert" means to prevent or turn away from something, which is opposite to adjusting to it.
Hence, Option 3: adapt -> The ability to adapt is a fundamental biological concept referring to how organisms modify their behavior, physiology, or structure to survive in changing environments. This is the standard terminology used in ecology and evolutionary biology. -> correct