Find the Radius of Convergence and the Interval of Convergence $$\sum _ { n = 0 } ^ { \infty } \frac { ( 7 x ) ^ { n } } { n ! }$$

Multiple Choice

Find the radius of convergence and the interval of convergence of the power series.
$$\sum _ { n = 0 } ^ { \infty } \frac { ( 7 x ) ^ { n } } { n ! }$$

A) $R = 7 , I = ( - 7,7 )$
B) $R = 0 , I = \{ 0 \}$
C) $R = 7 , I = [ - 7,7 ]$
D) $R = \infty , I = ( - \infty , \infty )$