Answer:
The correct option is;
C. All its mechanical energy is transformed into other forms of energy
Step-by-step explanation:
The given parameters are;
The nature of the system of the pendulum clock = Closed system
Present condition of the pendulum = Motionless
Initial condition = Moving
The principle of conservation of energy states that the sum of energy present in a closed system is always constant, as such, energy can neither be destroyed or created
Therefore, all the initial energy of motion of the pendulum which is known as mechanical energy, consisting of both potential and kinetic energy which resulted in the clock operation when the pendulum was in motion, has been transformed into other forms of energy which is shown by the at rest position having no motion, hence to kinetic energy, and no relative height to its location at rest, therefore, no relative potential energy.
Therefore, because the initial mechanical energy is now 0, going by the principle of energy conservation, all the mechanical has been transformed into other forms energy.