Reactants *A* and *B* shows I order decomposition individually. If [A0]=8[B0] and t1/2 for *A* and *B* are 10 and 20 minutes respectively then if both starts decomposing at the same time, after how much minute the concentration of both *A* and *B* will be same :
a. 20
b. 40
c. 60
d. 80