A.A critic decides that Doré's point of view is stronger after viewing the illustration of the Minotaur from Dante's Inferno.
B.A playwright must choose which actors would best portray Dante and Virgil in his new production of Dantes inferno
C.A Teacher reads the inferno aloud to her students to help them better understand the plot
D.After Viewing blakes illustration of the suicides and harpies a painter decides to recreate the same scene
First, it would be wise to define what we call "medium" on this context. A "medium" here is referred as the means or type of artistic vehicle an artist uses to make its work reach the audience. It can be a book, a play, a poem, a movie, a ballet dance, a painting, a sculpture, etc.
Having mentioned this, now let us answer the question of which example best describes a change of medium and then explain the reason for the selection:
B.A playwright must choose which actors would best portray Dante and Virgil in his new production of Dante’s inferno
The change of “media” occurs when changing the work or Dante Alighieri from the paper to the theatre. In other words, the change from literary art to visual art in this case, is the change of “media”.