Organophosphate is used to control:

Correct option is D

Correct Answer: (d) Crustaceans
Explanation:
→ Organophosphates (like DDVP, Malathion) act on the nervous system of crustacean ectoparasites, such as Argulus and Ergasilus.
→ They inhibit acetylcholinesterase, causing paralysis and death of external crustacean parasites.
→ Widely used in aquaculture ponds for ectoparasite control.
Information Booster:
→ Overuse can harm non-target organisms and reduce oxygen levels.
Additional Information:
(a), (b), (c): Organophosphates are ineffective against nematodes, endoparasites, and digenetic trematodes.