If two electrons are forced to come closer to each other, then the P.E of the system of 2 electrons will

We know from concept that

Electric potential energy $U=\frac{1}{4\pi {\epsilon }_0}\frac{q_1{q}_2}{r}$

For two electron system separated by r

We have $U=\frac{+e^2}{4\pi {\epsilon }_{0}r}$

As you force the two electrons came closer r decreases so U will be increased.

So option (b) correctly evaluating the task

But we can evaluate that a, c, d as incorrect conclusions.