Find the standard form of the equation of the parabola with a vertex at the origin and a focus at (0, -4). a.)y = negative one divided by four x2 b.)y2 = -4x c.)y2 = -16x d.)y = negative one divided by sixteen x2

We have 
Parabola
with vertex (0,0) and   focus (0,-4)

we know that
is a vertical parabola that opens down
the standard form of the equation is of the form
(x-h)²=-4p(y-k)
where
(h,k) is the vertex----------> (0,0)
p is the distance from the vertex to the focus or directrix
in this problem 
p=4
(x-h)²=-4p(y-k)------> x²=-16y-------> y=-(1/16)x²

the answer is the option
D.)y = negative one divided by sixteen x2

see the attached figure

B. 16is the absolute value

The answer is 30 minutes to an hour