There are 45 number of cells with internal resistance of each cell is $0.5\mathrm{\Omega }.$  To get the maximum current through a resistance of $2.5\mathrm{\Omega },$  one can use m rows of cells, each row having n cells. The values of m and n are 

• A

  $\mathrm{m}=3,\mathrm{n}=15$

• B

  $\mathrm{m}=5,\mathrm{n}=9$

• C

  $\mathrm{m}=9,\mathrm{n}=5$

• D

  $\mathrm{m}=15,\mathrm{n}=3$