Ans: (B)
In isothermal process
$$
\begin{aligned}
&\mathrm{T}=\text { constant } \\
&\Delta \mathrm{U}=\mathrm{n} \mathrm{C}_{\sqrt{ }} \Delta \mathrm{T}
\end{aligned}
$$
$$
\begin{aligned}
&\text { In isobaric expansion [ } \therefore \mathrm{P}=\text { constant }] \\
&\therefore \mathrm{V} \propto \mathrm{T} \therefore \text { T increases due to expansion } \Rightarrow \text { increase in internal energy }
\end{aligned}
$$
