How many covered trash cans of solid construction must a salon have?

A salon must have a number of covered trash cans that are of solid construction, which is often described as needing to be "adequate." This means that the facility should provide enough containers to sufficiently manage waste generated during operations, while ensuring cleanliness, hygiene, and compliance with health regulations.

In this context, the term "adequate" is key because it does not specify an exact number but rather emphasizes the necessity to have enough containers to accommodate the waste without overwhelming a single can or causing spillage. This approach allows for flexibility based on the size of the salon and the volume of waste produced, promoting both sanitation and safety for both employees and clients.

The other options suggest specific numbers or lack of necessity, which do not align with regulatory standards that prioritize cleanliness and proper waste management. Thus, having an adequate number of solidly constructed covered trash cans is essential for maintaining a professional and hygienic environment in a salon.