The correct answer is C. both (A) and (B).
When a transmission line is energized, both current and voltage waves propagate on it. The current wave is the result of the flow of electrons through the conductor, while the voltage wave is the result of the difference in electric potential between the two ends of the conductor. The two waves are coupled together and travel at the same speed.
The current wave is the result of the flow of electrons through the conductor. The electrons are attracted to the positive terminal of the voltage source and repelled by the negative terminal. This causes them to move through the conductor, creating a current. The current wave is a traveling wave, which means that it moves along the conductor at a constant speed.
The voltage wave is the result of the difference in electric potential between the two ends of the conductor. The positive terminal of the voltage source has a higher electric potential than the negative terminal. This difference in potential causes electrons to flow through the conductor, creating a current. The voltage wave is also a traveling wave, which means that it moves along the conductor at a constant speed.
The current and voltage waves are coupled together. This means that the current wave affects the voltage wave, and the voltage wave affects the current wave. The coupling between the two waves is caused by the resistance of the conductor. The resistance of the conductor causes the current wave to lose energy, which is converted into heat. This loss of energy causes the voltage wave to decrease.
The two waves travel at the same speed. This is because the speed of a wave is determined by the properties of the medium through which it travels. In this case, the medium is the conductor. The speed of a wave in a conductor is determined by the resistivity of the conductor and the length of the conductor.
The answer to the question is C. both (A) and (B).