Answer:
*helps*
Step-by-step explanation:
need anymore help?
Vertex form is

We're practically in vertex form,

That's a vertex at x=0, y=4, (0,4)
choice C
You take a right triangle and find the lengths of the two sides that are vertical and horizontal. Then, using the formula a^2 + b^2 = c^2, find the length of C
(aka: Hypotenuse)