Concept:A silo is an airtight, pest-proof storage structure that protects grains from insects.
Explanation:Maize grains are best protected from insect attacks when kept in a silo.
A silo provides a clean, dry, and closed environment.
This prevents insects from entering and damaging the grains.
Storing in a room, leaving grains on cobs, or covering with leaves does not give reliable protection against insects.
These methods allow insects to reach and infest the grains easily.
Answer:A. keeping in a silo