What type of appliances can be installed in storage closets according to prohibited locations?

The correct answer identifies that solid fuel-fired appliances are specifically restricted from being installed in storage closets according to the prohibited locations outlined in the mechanical code. Solid fuel-fired appliances, which include wood or coal-burning units, have different operational and safety requirements due to the combustion processes they involve. These appliances produce smoke and exhaust gases that need adequate ventilation; installing them in a confined space such as a storage closet can lead to dangerous conditions, including the buildup of harmful gases and increased fire risks. Hence, the code prohibits their installation in such environments to ensure safety and proper functioning.

In contrast, the other options do not accurately reflect the restrictions. While some appliances might have their own limitations or preferred installation settings, the focus here is specifically on solid fuel-fired appliances and their unique risks associated with confined spaces. This distinction is crucial for compliance with safety regulations and ensuring that appliances are installed in a way that minimizes hazards.