The carp that does not release egg inside a hapa or breeding enclosure even after injection is:

Correct option is B

Correct Answer: (b) Silver carp
Explanation:
→ Silver carp often fail to release eggs inside confined enclosures (hapas) even after hormonal induction.
→ They require strong flowing water conditions to spawn naturally.
Information Booster:
→ Silver carp are riverine species with high water current dependency.
Additional Information (Other Options):
(a), (c), (d): These species breed successfully in hapas with hormone treatment.