Answer:
1/16
Explanation:
If you plot the vertex and the point, you'll find that the point lies above the vertex, thus, the parabola opens upwards, so the vertex form of this parabola will be:

In order to solve for the leading coefficient, we first need to solve for p. We will fill in the vertex form with all the info we have:

which simplifies to
and
4p = 16 so
p = 4
Now we can rewrite the parabola using this value of p:
and

We divide both sides by 16 to get
and to finish it off properly:

As you can see, the leading coefficient is 1/16