Correct option is C
Correct answer – (c) Activated kaolinite clay is mainly used in stored grain protection. It acts physically by coating insects and causing dehydration. Hence, it is useful against storage pests.
Information Booster / Facts Kaolin-based dusts reduce insect movement and feeding. They are non-toxic and residue-free.
Why other options are incorrect (a) Subterranean pests are not controlled effectively by kaolin dust. (b) Leaf feeders are better managed by sprays/biopesticides. (d) Stem borers are internal feeders, not controlled by clay dust.