Which of the following is commonly used equipment by ramp agents?

Baggage carts and belt loaders are essential pieces of equipment commonly used by ramp agents in their daily operations at airports. Ramp agents are responsible for handling the loading and unloading of luggage and cargo from aircraft. Baggage carts facilitate the transportation of baggage from the check-in area to the aircraft, allowing for efficient movement and organization of luggage. Similarly, belt loaders are used to move baggage directly into and out of the cargo holds of airplanes, streamlining the process and ensuring that items are loaded correctly and promptly.

This combination of equipment is vital for the ramp's productivity and safety, as it helps manage the flow of baggage while minimizing the risk of damage to both the luggage and aircraft. In contrast, the other options, such as passenger boarding bridges, runway de-icing vehicles, and air conditioning units, are more specialized equipment used in different contexts at the airport. While they play important roles in airport operations, they are not typically part of the ramp agents' responsibilities or day-to-day equipment usage.