Final answer:
The respiratory inlet covering that completely covers the head and neck, and may also cover portions of the shoulders and torso, is called a respirator (option C).
Step-by-step explanation:
The respiratory inlet covering described as completely covering the head and neck and potentially covering portions of the shoulders and torso is commonly known as a respirator. The correct answer to the student's question would be option C: Respirator. Respirators such as the CPAP device for sleep apnea and protective hoods used by firefighters, like the Nomex hood, are designed to provide a breathable air supply or filter out harmful particulates, providing protection to the respiratory system. In contrast, face masks may cover the nose and mouth to filter the air but do not cover the entire head and neck, helmets are primarily for impact protection, and scarves are generally used for warmth and not specific respiratory protection.