Which is an example of a type of battery?

The wet cell, commonly known as a car battery, is indeed a classic example of a battery. A wet cell battery consists of lead plates immersed in an electrolyte solution, typically sulfuric acid, which facilitates the chemical reaction needed to generate electrical energy. This system is widely used in vehicles to provide the necessary power to start the engine and operate electrical components.

The other options represent different technologies rather than conventional batteries. A solar cell converts sunlight into electrical energy but does not store electricity, which is a function of batteries. Radioactive cells, while they do generate power from radioactive decay, are not conventional batteries and are often used for specialized applications, such as in space probes. Hydrogen fuel cells, on the other hand, generate electricity through a chemical reaction between hydrogen and oxygen but are part of a different technology framework compared to traditional batteries.

Thus, the wet cell exemplifies a well-understood form of battery technology that functions according to classic electrochemical principles, making it the correct answer.