Fill in the Blank with One of the Words or Phrases

Multiple Choice

Fill in the blank with one of the words or phrases listed below.

-The graph of $f ( x ) = a x ^ { 2 } + b x + c$ , where $a$ is not 0 , is a parabola whose vertex has an $x$ -value ofــــــــــــــــــ

A) $( h , 0 )$
B) $\pm \sqrt { b }$
C) $( h , k )$
D) $\frac { - b } { 2 a }$