Q: Some aviary species fly and others swim but, all endothermic tetrapod vertebrates share what trait?\nOptions:\n- (A) warm-blooded\n- (B) Weight\n- (C) fur and fat\n- (D) sweating\n- (E) Epidermis\n- (F) feathers\n- (G) retina\n- (H) four limbs
Let's think step by step below.

User
Birds are endothermic tetrapod vertebrates. Some birds fly and some birds swim, but all birds have feathers. Some aviary species fly and others swim but, all are endothermic tetrapod vertebrates.
Thus, the answer is (F).
Assistant