For the reaction of A + B → C + D, doubling the concentration of both the reactants increases the reaction rate by 8 times and doubling the initial concentration of only B simply doubles the reaction rate. The rate law for the reaction is

(a) r = K [A][B]²
(b) r = K [A][B]
(c) r = K [A]½[B]
(d) r = K [A]²[B]