The value of `3(cos theta-sin theta)^(4)+6(sin theta+cos theta)^(2)+4 sin^(6) theta` is where `theta in ((pi)/(4),(pi)/(2))` (a) `13-4cos^(4) theta` (b) `13-4cos^(6) theta` (c) `13-4cos^(6) theta+ 2 sin^(4) theta cos^(2) theta` (d) `13-4cos^(4) theta+ 2 sin^(4) theta cos^(2) theta`
A. `13-4cos^(6)theta`
B. `13-4cos^(4)theta+2sin^(2)thetacos^(2)theta`
C. `13-4cos^(2)theta+6cos^(4)theta`
D. `13-4cos^(2)theta+6sin^(2)thetacos^(2)theta`
