Apple wooly aphid resistant variety is

Answer: Option B

Apple woolly aphid resistant variety is Northern spy.
Woolly apple aphids infest roots, trunks, limbs, shoots, and occasionally fruit of apple trees. The bodies of these bark-feeding aphids are completely covered by masses of white, wool-like, waxy materials. This aphid is found in colonies on the aerial portions of the tree and on roots during winter.
The Malling-Merton series of rootstocks were developed to be resistant to woolly apple aphid, as was the Merton 793 selection, which is commonly used in the southern hemisphere. This resistance is based on a scion cultivar, 'Northern Spy'.