Suppose f$($x$)=15$x$6+14$x$2+2$sinxf$($x$)=15$x$6+41$x$2+2$sinx$.$

Then f$($x$)$f$($x$)=$

A$\mathrm{.}450$x$4+12$x$8$sinx$450$x$4+21$x$8$sinx

B$\mathrm{.}450$x$4+122$sinx$450$x$4+212$sinx

C$\mathrm{.}450$x$4+12$x$+2$sinx$450$x$4+21$x$+2$sinx

D$\mathrm{.}450$x$4+12+2$sinx$450$x$4+21+2$sinx

E$\mathrm{.}450$x$4+128$sinx$450$x$4+218$sinx