For the reaction `A + B rarr C + D`, doubling the concentration of both the reactants increases the reaction rate by `8` times and doubling the initial concentration of only `B` ismply doubles the reaction rate. What is the rate law for the reaction ?
A. `r=k[A]^(1//2)[B]^(1//2)`
B. `r=k[A][B]^(2)`
C. `r= k[A]^(2)[B]`
D. `r=k[A][B]`