The correct answer is A. The system is at rest and no energy is stored in any of its components.
A zero initial condition 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 B is incorrect because the system can be working with zero stored energy even if the initial condition is not zero. For example, if the system is initially at rest and then a force is applied to it, the system will start to move and will have kinetic energy. However, the stored energy in the system will still be zero.
Option C is incorrect because the system can be working with a zero reference signal even if the initial condition is not zero. For example, if the system is initially at rest and then a reference signal is applied to it, the system will start to move. However, the reference signal will not affect the stored energy in the system.
Option D is incorrect because the initial condition is a specific value that is used to start the system. The initial condition can be zero, but it does not have to be.