Find the Standard-Form Equation for an Ellipse Which Satisfies the Given

Multiple Choice

Find the standard-form equation for an ellipse which satisfies the given conditions.
-An ellipse centered at the origin having focus at $( 8,0 )$ and eccentricity equal to $\frac { 1 } { 2 }$

A) $\frac { x ^ { 2 } } { 64 } + \frac { y ^ { 2 } } { 48 } = 1$
B) $\frac { y ^ { 2 } } { 256 } + \frac { x ^ { 2 } } { 192 } = 1$
C) $\frac { x ^ { 2 } } { 256 } + \frac { y ^ { 2 } } { 192 } = 1$
D) $\frac { x ^ { 2 } } { 64 } + y ^ { 2 } = 1$