Concept:Lines used to show equal values of a weather element on a map are given special names.Explanation:Sunshine duration refers to the number of hours of sunlight received in a place.A line that joins places receiving the same amount of sunshine on a map is called an isohel.Other similar lines include isohyets for rainfall and isonephs for cloud cover.Therefore, the correct option is Isohel.Answer:A. Isohel