Add the rational expressions and simplify.

$fraction numerator 4 over denominator x squared y end fraction plus space fraction numerator 2 over denominator x squared y end fraction$

A. $fraction numerator 4 x plus 2 x over denominator x squared y end fraction$

B. $fraction numerator 6 over denominator x squared y end fraction$

C. $fraction numerator 6 over denominator x y end fraction$

D. $fraction numerator 6 over denominator 2 x squared y end fraction$