Draining water targets non-mobile aquatic mosquito stages

Steps:

• Recall mosquito life cycle: eggs laid on water, larvae and pupae develop in water, adults emerge and fly.
• Identify aquatic stages requiring stagnant water for survival: eggs float on surface, pupae remain in water.
• Determine draining effect: removes water, destroying immobile eggs and pupae unable to escape.
• Match to options: egg and pupa stages are directly eliminated.

Why B is correct:

• Eggs and pupae are strictly aquatic and non-motile, per mosquito biology, so draining instantly kills them by habitat removal.

Why the others are wrong:

• A: Omits pupa; larvae survive briefly if water recedes slowly but are not the only target.
• C: Excludes egg; eggs are primary breeding site destroyed first.
• D: Includes adult; adults live on land and are unaffected by water drainage.

Final answer: B