The answer is b, but I don't know understand how this is done.

Matt synthesized a new polymer with the radical polymerization and get a molecular weight (MW) of 40,000g/ mole. The whole process took 48 hours to accomplish the reaction. If he would like to make the same polymer with radical polymerization with a MW no less than the current one in less than 5 hours, he can use (a) 4 times of monomer concentration and 4 times of initiator concentration. (b) 4 times of monomer concentration and 9 times of initiator concentration. (c) 3 times of monomer concentration and 16 times of initiator concentration. (d) 2.5 times of monomer concentration and 36 times of initiator concentration. (e) None of the above condition will be able to achieve the goal