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 formula $x = \frac { - b \pm \sqrt { b ^ { 2 } - 4 a c } } { 2 a }$ is called theـــــــــــــــــــ

A) quadratic inequality
B) completing the square
C) discriminant
D) quadratic formula