A Student Taking a Plant Physiology Class Is Interested in Investigating

A student taking a plant physiology class is interested in investigating what will happen if the apical bud is removed from a growing plant and supplementary hormones are introduced.
He set up his experiment with two groups of plants of the same species. In groups A and B, the apical buds were removed and the cut apical ends were wrapped with hormone-impregnated cotton. The plants were observed over a 5-week period for growth and development. In group A, many axillary buds and leaves appeared along the sides of the stem, and the plants had minimal root growth. In group B, minimal growth occurred in the shoot and roots, and no axillary buds formed.
-What hormone was in the cotton used to wrap the apical ends of the group B plants?

A) cytokinin
B) giberellin
C) abscisic acid
D) auxin