y = 2 sin x cos x
dy/dx =
2[sin x . d (cos x)/dx + cos x . d(sin x)/dx]
dy/dx = y' =
2[ sin x . (-sin x) + cos x . cos x]
y' = 2 [cos² x - sin² x]
y' = 2 cos 2x [cos²x - sin²x = cos 2x]
Hence, option C is correct!
Hope it helps...!!
