单选题：Given a set of activities $$S = \{ a_1, a_2, \cdots , a_n \}$$.

Given a set of activities $$S = \{ a_1, a_2, \cdots , a_n \}$$. Each $$ a_i$$ takes place during a time interval $$ [s_i, f_i)$$.
If an instance $$S$$ given as the following, the maximum-size of mutually compatible activities is __. @[B](2)





A. 4
B. 5
C. 6
D. 7




A.4
B.5
C.6
D.7


答案：B