涛涛gwd-23-Q30:求助谢谢

gwd-23-Q30:

gwd-23-Q30:

There are 8 books on a shelf, of which 2 are paperbacks and 6 are hardbacks.  How many possible selections of 4 books from this self include at least one paperback?    Answer:c

A.   40

B.    45

C.   50

D.   55

E.    60    我选的是D，请问为什么是C，谢谢大家