a
(a)If $m$ $=$ Number of rows
and $n$ $=$ Number of cells in a row
Then $m × n = 100$ .....$(i)$
Also condition of maximum current is $R = \frac{{nr}}{m}$
$==>$ $25 = \frac{{1 \times n}}{m}$
$==>$ $n = 25 m$ .....$(ii)$
On solving $(i)$ and $(ii)$ $m = 2$