Determine the intervals on which the function is increasing, decreasing, and constant.
a coordinate axis is drawn with a parabola pointing up that has vertex of 0,3.

a. increasing x < 0; decreasing x > 0
b. increasing x > 0; decreasing x < 0
c. increasing x < 3; decreasing x > 3
d. increasing x > 3; decreasing x < 3