Find All the Critical Numbers of the Function $g(x)=7 x+\sin (7 x)$

Multiple Choice

Find all the critical numbers of the function. $g(x) =7 x+\sin (7 x)$

A) $\frac{\pi n}{7}$
B) $\frac{\pi(2 n+1) }{28}$
C) $\frac{\pi(2 n+1) }{7}$
D) $\frac{\pi}{14}$
E) None of these