Which of the diagrams shown in the figure represents the variation of total mechanical energy of a pendulum oscillating in water as a function of time?

Which of the diagrams shown in the figure represents the variation of the total mechanical energy of a pendulum oscillating in water as a function of time?

In damped $SHM$,the $SI$ unit of damping constant is

Obtain the differential equation of forced oscillation.

Resonance is an example of

$Assertion :$ Resonance is a special case of forced vibration in which the natural frequency of vibration of the body is the same as the impressed frequency of external periodic force and the amplitude of forced vibration is maximum.
$Reason :$ The amplitude of forced vibrations of a body increases with an increase in the frequency of the externally impressed periodic force.