A salon must be separated from any living or sleeping quarters by what?

The correct choice highlights the requirement that a salon must have complete partitioning and utilize solid, self-closing doors to ensure a clear separation from any living or sleeping quarters. This standard is established to maintain hygiene, privacy, and a professional environment conducive to esthetic practices.

Solid, self-closing doors contribute to these objectives by minimizing the risk of cross-contamination and ensuring that the salon remains a distinct space, free from distractions and potential health concerns that living or sleeping areas may introduce. Complete partitioning further enhances this separation by blocking sound and providing a more private atmosphere for clients receiving services, vital in the esthetics industry.

Other options lack the necessary elements specified in regulations, such as the requirement for solid and self-closing features, which are critical for maintaining compliance with health and safety standards in a salon environment.