A) regenerate injured parts
B) protect itself against invading parasite
C) harden its mantle cavity
D) isolate damaged tissues of the body
Correct Answer: B
Solution :
The pearl oysters produce pearl as an adaptation against outside materials. When a foreign material such as a sand, grain or parasite happens to enter the body, it adheres with the mantle. The mantle epithelium at once grows over the material in the form of sac and encloses it. This mantle epithelium starts secreting concentric layers of nacre around the foreign substances. The completed structure is called pearl.
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