The answer is: D
Explanation
The correct option is D: Yes, all of the robbers can be charged because the act of one man in discharging the gun was in pursuit of the common intention of all of them to rob the bank.
This is because, according to Section 34 of IPC, 1860, when a criminal act is done by several persons in furtherance of the common intention of all, each of such persons is liable for that act in the same manner as if it were done by him alone. The common intention implies a pre-arranged plan and an active participation in the commission of the crime.
In this case, the four men had a common intention to rob the bank, and they acted in concert to execute their plan. The fact that they agreed to try not to hurt anyone does not negate their common intention, as it was only a contingent possibility and not a part of their plan. The act of discharging the gun was done in furtherance of their common intention to rob the bank, and it resulted in the death of the bank employee. Therefore, all of them are equally liable for the murder, irrespective of who actually fired the gun.