What is \(\smallint {\sin ^3}x\cos x\;dx\) equal to?

• A. cos4 x + c
• B. sin4 x + c
• C. \(\frac{{{{\left( {1 - {{\sin }^2}x} \right)}^2}}}{4} + c\)
• D. \(\frac{{{{\left( {1 - {{\cos }^2}x} \right)}^2}}}{4} + c\)