The lion is most similar to a tiger, because both are members of the same genus. The gray wolf and coyote belong to different genera, the aardwolf belongs to a different family, and the whale belongs to a different order.
The answer is; endoskeleton
An endoskeleton allows for smooth and steady growth unlike in an invertebrate with an exoskeleton that needs to shed their skeleton during irregular growth spurts. An endoskeleton is significant for leveraging (like an anchor) skeletal muscles hence enabling the animals to grow big and is able to support their own weight.
Blue is the correct answer