Myrobalan B is a rootstock of:

Correct option is D

Myrobalan B is a clonal rootstock used for plum cultivation. It is tolerant to root-knot nematodes and adapts well to different soil conditions. It also imparts vigor to scion varieties and ensures good anchorage. Rootstocks like Myrobalan are selected based on their compatibility and disease resistance. Apple, pear, and cherry have their specific rootstocks. Thus, it is used primarily for plums, making option (d) correct.