What is f(x) = 8x2 + 4x written in vertex form?

f(x) = 8(x + one-quarter) squared – one-half
f(x) = 8(x + one-quarter) squared – one-sixteenth
f(x) = 8(x + one-half) squared – 2
f(x) = 8(x + one-half) squared – 4