Compute the derivative of the function f$($x$)=$x$(4$x$2)$f$($x$)=$x$(4$x$2).$

Select one:

a$.$

$$xx$$xx

b$.$

x$(4$x$2)2$xx$$x$(4$x$2)2$xx

c$.$

$45$x$22$x$1/245$x$22$x$1/2$

d$.$

$4$x$2$xx$$