The correct answer is: D. get minimum overshoot.
Damping is a process that reduces the amplitude of oscillations in a system. In a ballistic galvanometer, damping is used to reduce the overshoot that occurs when the galvanometer is subjected to a sudden change in current. The amount of damping is controlled by the value of a resistor that is placed in series with the galvanometer coil. A smaller value of resistance results in less damping and a larger overshoot.
A. Getting the first deflection large is not the purpose of damping. In fact, damping can actually reduce the first deflection by causing the galvanometer to settle to its final position more quickly.
B. Making the system oscillatory is not the purpose of damping. In fact, damping is used to prevent the system from oscillating.
C. Making the system critically damped is not the purpose of damping. In fact, critically damped systems have no overshoot, but they also take the longest to settle to their final position.