单选题：In a disjoint set problem, given a set of $$m$$ elements $$S$$ =

In a disjoint set problem, given a set of $$m$$ elements $$S$$ = { 1, 2, 3, ..., $$m$$ } and $$n$$ ( $$ 0
A. at leatst $$m$$
B. exactly $$n$$
C. exactly $$m-n$$
D. at least $$m-n$$




A.at leatst $$m$$
B.exactly $$n$$
C.exactly $$m-n$$
D.at least $$m-n$$


答案：D