In the reaction `A + B rarr C+D`, the concentration of `A` and `B` are equal and the rate of the reaction is rate `= k[A][B]`. The integrated rate equation for this reaction is
A. `k = (x)/(t(a-x))`
B. `k = (xa)/((a-x))`
C. `k = (1)/(t).(x)/(a(a-x))`
D. `k = (1)/(t).(x)/(a(x-a))`