Aphids and mosquitoes can be controlled by, respectively:

The correct answer is Option (1) → Ladybirds and dragonflies

Biocontrol means using living organisms to control pests instead of chemicals. The order of the pair matters: the first controls aphids, the second mosquitoes.

Option (1) Ladybirds and dragonflies — Correct. In biological control, natural predators are used against pests. Ladybirds (lady bird beetles) control aphids, and dragonflies are useful to get rid of mosquitoes.

Option (2) Ladybirds and butterflies — Incorrect. Ladybirds fit, but butterflies feed on nectar, not on mosquitoes.

Option (3) Caterpillars and birds — Incorrect. Caterpillars are pests themselves; they eat leaves, not aphids.

Option (4) Birds and dragonflies — Incorrect. Dragonflies fit, but NCERT names the ladybird, not birds, for aphids.

NCERT Extract:
Microbes as Biocontrol Agents – …