The onion varieties grown in plains are categorized as ________.

Correct option is A

Onion Photoperiod Classification:
✅ Short day onions are suited for tropical and subtropical plains, like most parts of India.
These onions bulb when daylight is about 10–12 hours.
❌ Long day onions require 14–16 hours of daylight (temperate zones).
❌ Intermediate type – Bulb at 12–14 hours of light.
❌ Day neutral – Rare; bulb regardless of day length.