Which of the following must NOT be present in a prep room according to regulations?

The correct answer is that an open window must not be present in a prep room according to regulations. The primary focus in a prep room is to maintain a controlled environment that adheres to health and safety standards. Having an open window can compromise this control by introducing external elements such as contaminants, temperature changes, or pests, which could pose a risk to both the deceased and the personnel working in the area.

Other items like an embalming table, germicidal soap, and a clean sheet are essential for the preparation of remains and ensuring hygiene standards. The embalming table is necessary for conducting embalming procedures, while germicidal soap helps maintain sanitation and cleanliness. A clean sheet is used to cover the deceased during preparation, ensuring dignity and respect. Each of these required items plays a critical role in the process of handling and preserving human remains, whereas an open window does not conform to the necessary regulations for a safe and sanitary prep room.