Ranking is done in a disjoint data structure. That is, the smaller one is planted in the larger one. If equal, the right is added to the left. For example, in union(1, 2), if the order of the two sets is equal, the set of 2 is added to 1. Accordingly, after 1, 2, 3, 4, 5, 6, 7, 8, 9 elements are set with a set-set (1,2), union(3,4), union(3,5), union( 1 , union(3,6), union(8,9), union(3,1), modifiers, what's the buildable tree? A-1 B-2 C-3 D-4 E-5