Who Are Marion Morrison, Issur Danielovitch Demsky, and Archibald Leach

Who are Marion Morrison, Issur Danielovitch Demsky, and Archibald Leach?

A) movie stars of the silent era
B) the original names of movie stars from the studio system era
C) the names of the three leads in the 1946 Best Picture winner, The Best Years of Our Lives
D) the heads of MGM, Paramount, and Columbia in the studio system era
E) the three individuals who devised the method style of acting