Trenching around the field is recommended for the control of the insect pests:

Correct option is C

Trenching is a mechanical control method used to create barriers that prevent the movement or migration of certain insect pests.
Trenching is effective against:
· Red hairy caterpillar (Amsacta spp.):
· Larvae emerge in large numbers and migrate across fields.
· Trenches trap and prevent them from spreading.
· Locusts:
· In their nymphal (hopper) stage, they march in groups.
· Trenches act as barriers where they can be trapped and killed before they mature and take flight.
✅ Hence, trenching is recommended for both pests as a preventive field sanitation measure.
�� Correct answer is (c) Both Red hairy caterpillar and Locust.