The correct answer is: D. system is at rest and no energy is stored in any of its components.
A zero initial condition for a system means that the system is at rest and no energy is stored in any of its components. This means that the system is not moving and there is no potential energy stored in the system.
Option A is incorrect because the input reference signal is not necessarily zero for a system with a zero initial condition. The input reference signal is the signal that is used to control the system. For example, if the system is a motor, the input reference signal might be the voltage that is applied to the motor.
Option B is incorrect because the stored energy in a system is not necessarily zero for a system with a zero initial condition. The stored energy in a system is the energy that is stored in the system’s components, such as the springs and masses in a mechanical system.
Option C is incorrect because the initial movement of moving parts in a system is not necessarily zero for a system with a zero initial condition. The initial movement of moving parts in a system is the movement of the system’s components at the beginning of the time interval.
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