Find the Derivative Of $f ( x ) = \cos x - \sin x$

Multiple Choice

Find the derivative of $f ( x ) = \cos x - \sin x$

A) $\sin x + \cos x$

B) $- \sin x + \cos x$

C) $\sin x - \cos x$
D) $- \sin x - \cos x$
E) $2 \sin x$
F) $2 \cos x$
G) $- 2 \sin x$

H) $- 2 \cos x$