The correct
answer is: D. both a and bIn an underdamped system, the transient response will exceed the value of the input at times during the transient period. This is because the system will oscillate around the steady-state value before settling down. The steady-state will be reached faster than if the system is overdamped, because the system will not oscillate as much.
Option A is correct because the transient response will exceed the value of the input at times during the transient period. This is because the system will oscillate around the steady-state value before settling down.
Option B is also correct because the steady-state will be reached faster than if the system is overdamped, because the system will not oscillate as much.
Option C is incorrect because the present overshoot is not zero. The present overshoot is the maximum value that the output exceeds the steady-state value. In an underdamped system, the present overshoot is always greater than zero.
Option E is incorrect because both options A and B are correct.