Which of the following are common types of circuit breakers used in switchgear?

The correct answer identifies common types of circuit breakers that are widely used in switchgear applications. Air circuit breakers, for instance, operate by using air as the medium for arc quenching and are typically employed in high-voltage environments because of their simplicity and reliability. Oil circuit breakers utilize oil for both insulation and arc quenching, making them suitable for outdoor applications and in situations where moisture may be a concern. Vacuum circuit breakers employ a sealed environment where the contacts are enclosed in a vacuum, effectively extinguishing the arc when the circuit opens, thus providing a compact and maintenance-free solution.

These types are particularly noted for their specific characteristics, such as performance under various environmental conditions, capacity for high interrupting ratings, and effective arc extinguishing methods. This versatility is crucial in providing safety and reliability in electrical distribution systems. The other answer choices present types of circuit breakers that either do not exist in the conventional sense or focus more on operational modes rather than widely recognized, standardized categories used in switchgear.