5. We know that $1+2+3+4=10$. It is also true that $1^{3}+2^{3}+3^{3}+4^{3}=10^{n}$ for some integer $n$. What is this integer?
A 1
B 2
C 3
D 4
E 5
5. B It is given that $1^{3}+2^{3}+3^{3}+4^{3}=10^{n}$. So $10^{n}=1+8+27+64=100=10 \times 10=10^{2}$. Hence $n=2$.