Which of the following is a common application of a DC generator?

A common application of a DC generator is providing power supply for various systems that require direct current, and elevators often use direct current motors for their operation. DC generators can efficiently produce the necessary voltage and current for these motors, ensuring they operate smoothly and reliably.

In the case of elevators, the ability of a DC generator to maintain consistent output under varying loads makes it particularly effective. Electric motors in elevators not only need to accelerate and decelerate smoothly but also require a stable power supply for continuous operation. DC generators are well-suited for these requirements due to their design and output characteristics.

While there are other applications mentioned, such as backup power and battery chargers, which are valid for various electrical systems, the typical application of a DC generator in operating direct current motors like those found in elevators highlights its specific capabilities and benefits in that context.