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. $$\begin{array} { l l l l } \text { quadratic formula } & \text { quadratic } & \text { discriminant } & \pm \sqrt { b } \\\text { completing the square } & \text { quadratic inequality } & ( h , k ) & ( 0 , k ) \\( h , 0 ) & \frac { - b } { 2 a } & &\end{array}$$
-The graph of $x ^ { 2 } + k$ has vertex_______

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