What is the sum of the rational expression below? 3x/x+2 + x/x+4
A. 4x^2 +14x/x^2 + 6x + 8
B. 4x/2x + 6
C. 3x^2/x^2 + 8
D. 4x^2 + 4x +8/x^2 + 6x +8