Which of the following comprises Group U occupancies?

Group U occupancies are defined as structures that are typically accessory to a residential or commercial use and are often not occupied as a primary function but instead serve auxiliary purposes. This classification commonly includes structures like carports, sheds, and greenhouses, which are utilized for various support functions such as vehicle storage, gardening, and storage of equipment or materials.

All three options—carports, sheds, and greenhouses—fall within the definition of Group U occupancies. Carports provide a designated area for parking vehicles, sheds often function as storage spaces for tools or gardening supplies, and greenhouses serve as structures for growing plants, all of which are accessory uses that do not constitute a primary occupancy.

Therefore, the correct answer, which encompasses A, B, and C, aligns with the definition of Group U occupancies as they all represent structures that support other primary uses but are not designated for habitation or commercial activities in their own right.