The step response of a circuit is seen to have an oscillatory behaviour at the output with oscillations dying down after some time. The correct inference(s) regarding the transfer function from input to output is/are

• A. that it is of at least second order.
• B. that it has at least one pole-pair that is underdamped.
• C. that it does not have a real pole.
• D. that it is a first order system.