To Insure Growing the Same Variety of Apple,which of the Following

To insure growing the same variety of apple,which of the following do large-scale apple growers do?

A) hand pollinate compatible varieties
B) only plant seeds from the tree with the desirable variety
C) graft stems from desirable varieties to hardy rootstock
D) spray crops heavily with auxin and ethylene
E) prevent bees from cross-pollinating the desirable trees with ones that are less desirable