Which of the following best describes the term "high-voltage transmission"?

High-voltage transmission refers to the practice of transporting electrical energy over long distances using high-voltage levels. This method is employed primarily to improve efficiency, as higher voltages reduce the amount of current required for the same power flow. When transmission lines operate at higher voltages, the I²R losses (where I is current and R is resistance) in the conductors decrease significantly, allowing more power to be transmitted over longer distances without excessive energy loss.

This concept is pivotal in modern electrical grids, as it enables the efficient delivery of electricity from power generation sources, often located far from consumption centers, to where it is needed most. High-voltage transmission systems, therefore, play a crucial role in enhancing the reliability and functionality of the entire electricity supply network.

The other choices do not encapsulate the concept of high-voltage transmission correctly. Low voltage is associated with safety but does not contribute to efficiency. Multiple phases can help with current stabilization but are not exclusively tied to high-voltage transmission. Lastly, photovoltaic cells are related to renewable energy generation rather than the specific concept of high-voltage transmission.