If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively ?

A. [xD/(RD + 1)], [RD/(RD + 1)]
B. [RD/(RD + 1)], [xD/(xD + 1)]
C. [xD/(RD + 1)], [(RD + 1)/RD]
D. None of these