If a proton is brought towards an electron from infinity, the potential energy of the system will

decrease

The correct answer is Option (1) → decrease

The potential energy of two point charges q1 and q2 separated by distance r is:

$U = \frac{1}{4 \pi \epsilon_0} \frac{q_1 q_2}{r}$

Given q1 = +e (proton), q2 = -e (electron). So $q_1 q_2 = -e^2 < 0$

At infinity: $U_\infty = 0$

As proton is brought closer to electron (r decreases), $U = -\frac{e^2}{4 \pi \epsilon_0 r} < 0$

Potential energy decreases (becomes negative) as proton is brought towards electron.