Rewrite with only sin x and cos x.
sin 3x - cos x (6 points)

Select one:
a. 2 sin x - sin3x - cos x
b. 2 sin x cos2x + sin x - 2 sin3x - cos x
c. 2 sin3x cos4x + 1
d. 3 sin x cos x - sin3x - cos x