A nickel-cadmium cell has an operating voltage of about:

The correct answer, which indicates that a nickel-cadmium (NiCd) cell has an operating voltage of about 1.25 volts, is based on the typical voltage characteristics of this type of rechargeable battery. Nickel-cadmium cells are commonly used in applications where a stable voltage is needed throughout the discharge cycle. The nominal operating voltage of a fully charged NiCd cell is approximately 1.2 volts, but it can vary slightly depending on the specific design and usage conditions.

The value of 1.25 volts is often used as a practical representation of the cell's voltage when under load, as it reflects common usage scenarios. This makes it a useful value for designers and engineers when considering the power requirements of electronic devices that utilize NiCd cells.

Other options reflect different voltages associated with other types of batteries or misconceptions about the operating voltage of NiCd cells. For instance, 1.5 volts is typically the nominal voltage for alkaline batteries, while 2.0 volts is associated with lead-acid or other higher-voltage batteries. Recognizing the correct operating voltage is essential for ensuring compatibility and optimal performance in battery-operated devices.