Determine which relation is a function.

ANumber graph ranging from negative four to four on the x and y axes. A vertical line is drawn at x equals three.

BNumber graph ranging from negative four to four on the x and y axes. A parabola is drawn with a vertex at (zero, zero) and extending off to the right. C. Number graph ranging from negative four to four on the x and y axes. A circle is drawn with the point (two, one) on the perimeter of the circle.

DNumber graph ranging from negative four to four on the x and y axes. An absolute value function is drawn with a minimum at (zero, zero).