With another person on student A’s side. I’m sorry if I wasn’t able to help. Im trying my best from the information given. :)
Explanation:
It is given that,
Charge in the particle,
Work done by the force,
The kinetic energy of the particle,
(a) Using the conservation of energy to find the work done by the electric force. Let it is given by as :
(b) Let V is the electric potential. the work done by the electric charge per unit positive charge is called its electric potential. Mathematically,
Hence, this is the required solution.
The answer is d.... Knife.
Hope this helped :)