What is the equation of the quadratic graph with a focus of (3, 1) and a directrix of y = 5?

f(x) = one eighth (x − 3)2 + 3
f(x) = −one eighth (x − 3)2 + 3
f(x) = one eighth (x − 3)2 − 3
f(x) = −one eighth (x − 3)2 − 3