Step 1: Identify currents
From the diagram:
• Current in middle branch = $i_1$
• Current in bottom branch = $i_2$
• Current through top resistor $R$ = $i_1 + i_2$
Step 2: Apply Kirchhoff’s Voltage Law (KVL)
Consider loop containing $E_1$, $r_1$, and $R$.
Traversing the loop:
• Gain from battery = $+E_1$
• Drop across resistor $R$ = $(i_1 + i_2)R$
• Drop across $r_1$ = $i_1 r_1$
Step 3: Write KVL equation
\[
E_1 - (i_1 + i_2)R - i_1 r_1 = 0
\]
Conclusion:
This matches option (B).
Final Answer: Option (B)