Integrate: $\int \limits_0^{\frac{z}{2}} \sin ^4 x \cos ^6 x dx$

Question

$$\begin {array} {1 1} (a)\;\frac{5z}{256} \\ (b)\;\frac{3z}{512} \\ (c)\;\frac{3z}{256} \\ (d)\;\frac{3z}{1024} \end {array}$$