A generator develops am e.m.f of $120\;v$ and has a terminal potential difference of $115\;v$ when the as mature current is $25\;A$ What is the resistance of the as mature ?

Question

$\begin{array}{1 1} 0.2 \; \Omega \\ 2 \;\Omega \\ 20\;\Omega \\ 0.02\; \Omega \end{array} $