A dwarf rootstock of pear is

Answer: Option D

A dwarf rootstock of pear is Quince C. It is a semi-dwarfing rootstock suitable for bush trees in situations such as small gardens and allotments.
Quince rootstock is usually used for dwarf pears. The quince (Cydonia oblonga) has been used for centuries as a rootstock for pear.
Such stocks produce dwarf trees that are earlier bearing (with some varieties) than standard trees. Will grow to 2.5 - 3.5 m (8 - 12′) eventually. The fruit from dwarf trees may mature a bit early, but it is of good quality.