What is the primary limitation for a person applying for a commercial pilot certificate with a balloon rating that uses an airborne heater?

The primary limitation for a person applying for a commercial pilot certificate with a balloon rating that uses an airborne heater is indeed about the specific type of operation they are certified to perform. When a pilot receives a commercial balloon rating that specifically includes the use of an airborne heater, it indicates that their training and certification are tailored to operate balloons that utilize such equipment.

This limitation ensures that the pilot has the necessary knowledge and skills to manage the unique aspects of flying a balloon with an airborne heater, including understanding how to control the heating system, gauge fuel usage, and safely manage the associated flight dynamics. Therefore, the pilot is restricted to operating balloons that are equipped with this heating system, which directly correlates with the certification they have earned.

The other options would not accurately represent the limitations specified by the training and certification; for instance, being limited to hot air balloons in general or to tethered operations would not accurately capture the specific focus on operations involving an airborne heater.