Which of the following is true about carports?

The statement about carports being at least two sides open is accurate because the defining characteristic of a carport is its partial enclosure. A carport is generally designed to provide shelter for vehicles while maintaining openness for air circulation and ease of access. Many carports have at least one or two sides that are not fully enclosed, allowing for easier entry and exit of vehicles and contributing to ventilation.

In contrast, the other options do not accurately represent the typical construction or function of carports. A carport does not require only a roof, as it is defined by its structural form that includes being open on at least two sides. Saying that carports are always completely enclosed contradicts their very purpose, which is to provide shelter while maintaining an open design. Lastly, a carport can have side panels or be completely open, but it typically cannot have no sides at all, as that would categorize it more as an awning or simply a roof without the carport's defining features. Thus, the statement regarding the necessity of having at least two sides open is correct and aligns with the definition of what constitutes a carport.