Find the Standard Form of the Equation of the Parabola $y = 3$

Multiple Choice

Find the standard form of the equation of the parabola with the given characteristic and vertex at the origin. ​
Directrix: $y = 3$ ​

A) $y ^ { 2 } = - 12 x$
B) $y ^ { 2 } = x$
C) $y ^ { 2 } = 12 x$
D) $x ^ { 2 } = 12 y$
E) $x ^ { 2 } = - 12 y$