A skateboard is being designed for a competition. The halfpipe will be in the shape of a parabola and will be positiond above the ground such that its focus is 30 ft above the ground. Using the ground as the x-axis, where should the base of the halfpipe be positioned? Which equation best describes the equation of the halfpipe? ( fast giving 1)

A. (0, 60); y= 1/240 x^2 – 60

B. (0, 60) y= 1/240 x^2 + 60

C. (0, 15) y= 1/60 x^2 – 15

D. (0, 15) y= 1/60 x^2 + 15