To get maximum current through a resistance of $2.5\,\Omega $, one can use $m$ rows of cells, each row having $n$ cells. The internal resistance of each cell is $0.5\,\Omega $. What are the values of $n$ and $m$ if the total number of cells is $45$ ?
  • A$m= 3,\,n = 15$
  • B$m= 5,\,n = 9$
  • C$m= 9,\,n = 5$
  • D$m= 15,\,n = 3$
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