Solve the Formula $\frac { x ^ { 2 } } { a ^ { 2 } } + \frac { y ^ { 2 } } { f ^ { 2 } } = 1 ; y$

Multiple Choice

Solve the formula $\frac { x ^ { 2 } } { a ^ { 2 } } + \frac { y ^ { 2 } } { f ^ { 2 } } = 1 ; y$
for the indicated variable.

A) $y=\sqrt{f(2-x a) (1+x a) }, y=-\sqrt{f(2-x a) (1+x a) }$
B) $y=f \sqrt{\left(1-\frac{x}{a}\right) \left(1+\frac{x}{a}\right) }, y=-f \sqrt{\left(1-\frac{x}{a}\right) \left(1+\frac{x}{a}\right) }$
C) $y=f \sqrt{\left(a-\frac{x}{a}\right) \left(a+\frac{x}{a}\right) }, y=-f \sqrt{\left(a-\frac{x}{a}\right) \left(a+\frac{x}{a}\right) }$

D) $y=\sqrt{f\left(1-\frac{x}{a}\right) ^{2}}, y=-\sqrt{f\left(1-\frac{x}{a}\right) ^{2}}$

E) $Y=f(1-x a) (1+x a) , Y=-\sqrt{f(1-x a) (1+x a) }$