Find the Point of Inflection of the Graph of the Function

Multiple Choice

Find the point of inflection of the graph of the function $f ( x ) = 2 \sin \frac { x } { 7 }$ on the interval $[ 0,14 \pi ]$

A) $( 0,0 )$
B) $( 2 \pi , 0 )$
C) $( 8 \pi , 0 )$
D) $( 7 \pi , 0 )$
E) $( 7 \pi , 2 )$