8
7
6
5
Correct answer is A
nC3=n!(n−3)!3!
nP2=n!(n−2)!
nC3nP2=n!(n−3)!3!÷n!(n−2)!
n!(n−3)!3!×(n−2)!n!=(n−2)!(n−3)!3!
Note that (n−2)!=(n−2)×(n−2−1)!=(n−2)(n−3)!
(n−2)(n−3)!(n−3)!3!=1
n−23!=1⟹n−2=6
n=2+6=8
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