Which of the following roots means 'fatty plaque'?

The root "ather/o" specifically refers to 'fatty plaque', which is commonly associated with atherosclerosis, a condition characterized by the buildup of fats, cholesterol, and other substances in and on the artery walls. This plaque development can restrict blood flow, leading to serious cardiovascular issues. Understanding this term is crucial in the medical field, particularly in discussions related to heart health and circulatory diseases.

The other choices do not convey the same meaning: "lith" refers to stones or calcifications, "swelling" describes an increase in size due to fluid accumulation, and "fistula" denotes an abnormal connection between two organs or vessels that normally do not connect. Each of these terms pertains to distinct medical conditions or concepts and emphasizes the specific nature of "ather/o" in the context of fatty plaque.