Question

which of the following releases enzymes to break down the outer layer?
arrector pili muscles
acetylcholine
osteoclasts
endotherms

Explanation:

Arrector pili muscles are involved in hair - raising and not enzyme - release for breaking down outer layers. Acetylcholine is a neurotransmitter, not an enzyme - releasing entity for this purpose. Endotherms are organisms that regulate body temperature and have nothing to do with releasing enzymes to break down outer layers. Osteoclasts are cells that release enzymes to break down bone matrix (an outer - like layer in the context of bone structure).

Answer:

C. Osteoclasts