What trait enables and organism to keep its internal body temperature constant?
a. homothermy
b. endothermy
c. exothermy
d. orgothermy

Endothermy is the trait that enables an organism to keep its internal body temperature constant. For example, humans shiver to keep warm should they feel cold and want to maintain homeostasis. This would not apply to reptiles, as they are cold-blooded and warm their bodies through different means.

Covalent bond is the correct answer