n identical cells each of E and internal resistance r be connected in services The current through load resistance R

Question

$\begin{array}{1 1} (a)\;I= \frac{nE}{R-nr}\\ (b)\;I= \frac{nE}{R+nr} \\ (c)\;I= \frac{nE-R}{nr} \\ (d)\;I=\frac{E}{R+nr} \end{array}$