\(\mathop \smallint \limits_0^{2{\rm{\pi }}} {\sin ^5}\left( {\frac{{\rm{x}}}{4}} \right){\rm{dx}}\) is equal to
1
\(\frac{8}{{15}}\)
2
\(\frac{16}{{15}}\)
3
\(\frac{32}{{15}}\)
4
0
\(\mathop \smallint \limits_0^{2{\rm{\pi }}} {\sin ^5}\left( {\frac{{\rm{x}}}{4}} \right){\rm{dx}}\) is equal to