Which chemical-protective clothing is a single-piece garment that totally encloses the wearer?

The encapsulating suit is specifically designed to provide a high level of protection by enclosing the wearer completely. This type of garment is constructed to prevent the penetration of hazardous materials, thereby safeguarding the wearer from exposure to chemicals and harmful agents. The sealed design ensures that no contaminants can enter the suit, offering both respiratory protection and overall body coverage.

In contrast, a liquid splash suit primarily protects against splashes and may not completely encase the wearer, allowing for some exposure at the openings. A coverall typically covers the body but may not provide the same level of sealing as an encapsulating suit. Lastly, a negative pressure suit is designed for specific applications and environments, often involving controlled environments where maintaining a vacuum or negative pressure is necessary, rather than full enclosure from external hazards.

Thus, the encapsulating suit stands out as the appropriate choice for a chemical-protective garment that offers total enclosure, making it the best answer to the question.