To get the maximum current through a resistance of 2.5 ohm one can use m rows of cells, each row having n cells. The internal resistance of each cell is 0.5 ohm. What are the value of n and m if total number of cells is 45.
(1) 15, 3
(2) 3, 15
(3) 9, 5
(4) 5, 9
