Manikara hexandra (Khirni) is used as root stock for

Answer: Option B

Manilkara hexandra (Khirni) is used as root stock for Sapota. A rootstock is part of a plant, often an underground part, from which new above-ground growth can be produced.
Manilkara hexandra is a tree species in the tribe Sapoteae, in the family Sapotaceae. It is locally known as the Khirni tree in parts of Bangladesh and India. It is a slow-growing but fairly large evergreen species. It grows in tropical and temperate forests.