Focus has coordinates (0, a)
a = -3
Thus, 4a = 4(-3) = -12
Because a is negative, we know it will be a concave down or concave left parabola. Hence, A and D can be eliminated. And we know it has to be B because the directrix is the horizontal line y = 3. Hence, the equation of the parabola becomes:

or
The length of ab is D. 15
2t^2+1
Subtract t^2 from 3t^2 you get 2t^2
which is 2t^2+1 answer