Question

what is the typical composition of gallstones?
potassium
sodium chloride
calcium carbonate
cholesterol

Explanation:

Gallstones are typically composed of cholesterol. Cholesterol gallstones are the most common type. Potassium is an element not typically a major component of gallstones. Sodium chloride (table salt) is not a main component. Calcium carbonate can be part of some gallstones (like pigment stones which also have bilirubin), but cholesterol is more typical for the common type.

Answer:

cholesterol