Terai soil comes under which soil order?

Answer: Option B

Terai soil comes under Mollisol. Terai is a low land in a lowland region in northern India Soils which are mostly similar to mollisols but contain either continuous or discontinuous permafrost.
Mollisol is a soil type that has deep, high organic matter, nutrient-enriched surface soil, typically between 60 and 80 cm in depth, and this fertile surface horizon is called mollic epipedon.