Question Detail
Question
Earthworms must keep their skin moist by constantly secreting mucus, primarily for:
Correct Answer
Option B is the correct answer.
Detailed Explanation
Earthworms constantly secrete mucus to keep their skin moist, primarily for gaseous exchange. Oxygen and carbon dioxide must dissolve in the moisture layer before diffusing across the skin surface.
Hint
This moisture is essential for diffusion of respiratory gases across the body surface.