The concept tested here leads specifically to Liver. The liver is the largest gland and performs many metabolic functions. Similar organs and biomolecules may participate in the same body system but do not perform identical functions. The alternatives Thyroid, Pancreas and Pituitary are legitimate scientific terms, but each belongs to a different function, property, material or context. If the topic involves the human body, check organ and function; in chemistry, check composition and reaction; in physics, check quantity and unit; and in environmental science, check layer and process.