1,2,3 – conjecture, for the problem of weight choosability and which was posed by Karo’nski in 2004. Even though it is a unsolved problem in graph theory, someone proved it in some special cases of graphs. Bartnicki, Grytczuk and Niwczyk posed a more difficult conjecture: 3-weight choosable conjecture, and make a different approach for the problem. The main results of this thesis is to prove that complete r-partite graphs, cactus, cographs, and distance-hereditary graphs are 3-weight choosable.