Simplify the Following Expression Algebraically $7 \cos ( \pi + x )$

Multiple Choice

Simplify the following expression algebraically.​ $7 \cos ( \pi + x )$ ​

A) $- 7 \sin x$
B) $- 7 \cos x$
C) $7 \cos x$
D) $\frac { 3 } { 2 } \cos x$
E) $- \frac { 3 } { 2 } \cos x$