Find the Point(s) of Inflection of the Graph Of $f ( x ) = \cos ^ { - 1 } 7 x$

Multiple Choice

Find the point(s) of inflection of the graph of $f ( x ) = \cos ^ { - 1 } 7 x$ .

A) $( 1,0 ) , \left( 0 , \frac { \pi } { 2 } \right)$ , and $\left( 0 , \frac { \pi } { 7 } \right)$
B) $( 1,0 )$
C) $\left( 0 , \frac { \pi } { 7 } \right)$
D) $\left( 0 , \frac { \pi } { 2 } \right)$