An adaptation is a trait that enables an organism to survive and reproduce selects which species live in water or land ensures a particular species’ extinction keeps organisms changing in their environments

Option A, enables an organism to survive and reproduce

Explanation:

Adaptation is the mechanism through which an organism become enabled to survive and reproduce  in certain environmental condition.

For example - in older days "coil mosquito repellents" were used to kill the mosquitoes but eventually the mosquitoes have evolved and became resistant to the deadly effects of "coil mosquito repellent" . This resistance is a form of adaptation to the existing environmental condition. Thus, from here it is also clear that a species or organism adapts to a changing situation though natural selection process in order to become the "fittest for survival".

Therefore option A, is correct.

"d.) carbon dioxide and hydrogen sulfide"