Parabolas in the form of

open upwards or downwards.
Parabolas in the form of

open to the left or to the right.
Since this parabola opens upward, we know it must be in the form of

. Also, if the coefficient of 'x' is positive, it opens upward, but if it is negative, it opens downward. This parabola opens upward, so we know that the coefficient of 'x' must be positive. Therefore, our answer must be D,
