Which of the following activities is NOT legally permitted for a homeowner without a mechanical contractor license?

The choice indicating that a homeowner can work on their rental property without needing a mechanical contractor license is correct because Michigan law provides certain exemptions for homeowners when it comes to maintaining their own properties.

In Michigan, homeowners are typically allowed to perform their own maintenance and repairs on properties they own, including rental properties, as long as those activities do not require a licensed contractor. This empowers homeowners to handle various tasks without incurring additional costs associated with hiring a licensed professional.

On the other hand, activities such as the installation of a central air conditioning system and the installation of an underground LP tank fall under regulated practices, requiring a specific level of skill and licensed oversight due to safety and code adherence concerns. These activities may involve intricate system connections and safety measures that the general public may not be able to execute competently without proper training and licensing. Therefore, a homeowner would need a mechanical contractor license to legally perform those installations.

In summary, working on rental properties without a contractor license is legally permitted for homeowners, while other specified installations are regulated and require licensure.