Simplify (frac{x – 7}{x^2 – 9}) x (frac{x^2 – 3x}{x^2 – 49})

A.
(frac{x}{(x – 3)(x – 7)}) 
B.
(frac{x}{(x + 3)(x – 7)}) 
C.
(frac{x}{(x + 3)(x + 7)}) 
D.
(frac{x}{(x – 3)(x + 7)})
Correct Answer: Option C
Explanation
(frac{x – 7}{x^2 – 9}) x (frac{x^2 – 3x}{x^2 – 49})
= (frac{x – 7}{(x – 3)(x + 3)}) x (frac{x(x – 3)}{(x – 7)(x + 7)})
= (frac{x}{(x + 3)(x + 7)})