Concept:The question asks for the one-word name of a medical branch related to the kidneys.Explanation:The term “Nephrology” comes from “nephro” meaning kidney and “logy” meaning study.It deals with kidney function and kidney diseases.Neurology relates to the nervous system.Ethnology relates to cultures and ethnic groups.Ethology relates to animal behaviour.Therefore, the correct branch is Nephrology.Answer:Nephrology (Option A).