GWD23-Q30

[schang0601]

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?
A.40
B.45
C.50
D.55
E.60

請問答案有錯嗎？我選D
C2取1*C6取3+C2取2*C6取2=40+15=45
請問我有哪裡算錯嗎？
麻煩會的人替我解答，感激不盡！