Answer:
Reduce the distance by a factor of 4.
Step-by-step explanation:
The electric potential energy between two charged particle is given by :
![U=(kqQ)/(r)](https://img.qammunity.org/2021/formulas/physics/middle-school/79utz2i1j5a1gmvd7wpnnp04967a2ngpr3.png)
k is electric constant
r is distance between two positively charged particles
Electric potential energy is inversely proportional to the distance between charges. If we decrease the distance between charges by a factor of 4, the electric potential energy will increase by an factor of 4.
Hence, the correct option is (C).