Answer:
The correct answer is C. Only one cell layer is found in a blastula.
Step-by-step explanation:
A blastula is a multicellular embryo having a single-layer structure, a stage in the development of the embryo that the eggs of most animals pass through, as the final result of the process of egg crushing. This follows the morula stage and completes the cleavage. In the narrower sense, blastula is only the “bladder germ” that occurs in many animals and encloses a liquid-filled cavity, the so-called blastocoel.