Simplify $(\frac{1+n}{2}{)}^3$

Select one:

A$.(\frac{1}{2}+n{)}^3$

B$.\frac{(1+n{)}^3}{8}$

C$.\frac{1}{8}+n^3$

D$.(\frac{1+n}{2}{)}^3$

E$.(\frac{1}{2}+\frac{n}{2}{)}^3$