Answer B)
(n log n + n2)(n3+2)
=n4 log n + n5 + 2 n log n + 2 n2
for Big O $0\leq f(n)\leq cg(n)$
Here n4 log n + n5 + 2 n log n + 2 n2 $\leq$ 2n5
then n4 log n + n5 + 2 n log n + 2 n2 =O(n5)
Similarly,
(n!+2n)(n3+log(n2+1))=n!n3+n!log(n2+1)+2nn3+2nlog(n2+1)
=O(n!n3)
Say, if we take log in n! and 2n , we get n! growth rate >> 2n