What is a "sanatorium"?

A "sanatorium" refers to a facility designed to provide long-term care for individuals with chronic diseases, particularly those requiring rehabilitation or extended treatment, such as tuberculosis in the past. These institutions often combined medical care with a tranquil environment intended to promote healing and recovery, emphasizing rest and fresh air. The treatment provided in a sanatorium was typically holistic, focusing on both the physical and mental well-being of the patient.

The other options do not accurately describe a sanatorium. A synthetic sweetener pertains to a substance used to mimic the sweetness of sugar without the calories, which has no connection to the medical treatment of diseases. The term related to a type of stomach foulness refers to a condition rather than a facility, and the medical condition characterized by infestation describes a health issue, rather than a place dedicated to treatment. Hence, the first choice is the only one that aligns with the definition and purpose of a sanatorium.