If a{(frac{x + 1}{x – 2} – frac{x – 1}{x + 2})} = 6x. Find a in its simplest form

A.
x^{2} – 1 
B.
x^{2} + 1 
C.
x^{2} + 4 
D.
x^{2} – 4 
E.
1
Correct Answer: Option D
Explanation
a{(frac{x + 1}{x – 2} – frac{x – 1}{x + 2})} = a{(frac{(x + 1)(x + 2) (x – 1)(x – 2)}{(x – 2)(x + 2)})}
= 6
(frac{6x}{x^2 – 4}) = 6x
a = x^{2} – 4