What facilities must be conveniently located in each establishment?

The requirement for restroom facilities in each establishment stems from public health and safety regulations that aim to ensure that all individuals have access to proper sanitation. Having conveniently located restroom facilities is essential not only for comfort but also for the health and hygiene of both employees and clients. This availability of restrooms reflects a fundamental standard in professional and public spaces, promoting a safe and respectful environment.

In contrast, while storage closets, waiting areas, and break rooms may contribute to the functionality and comfort of an establishment, the provision of restroom facilities is typically mandated by law to ensure compliance with health regulations. Therefore, the correct answer emphasizes the necessity of restroom facilities as a fundamental requirement for any establishment.