The animal adaptation that happened before the others is the development of a coelom. The correct option is D.
What is adaptation?
Adaptation is a process of changing or suiting the environment for better survival. Adaptations are short-term and long-term. An animal modifies their body part and behavior according to its changing surroundings.
The coelom is the body cavity in animals. They save the internal organs of the body, and they are filled with fluid. In some animals, they act as skeletons, like in worms.
The coelom is cavities of the body, and they were adapted earlier than other organs like lungs or skulls.
Thus, the correct option is D. Development of a coelom.
To learn more about adaptation, refer to the below link:
https://brainly.com/question/14420984
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