The passage discusses Valdez quite a bit in the second paragraph, which gives us a hint that this is where we should be focusing. As mentioned in lines 17-22 of the passage, "Valdez gathered a group of striking farm workers and asked them to talk about their working conditions...to illustrate what happened on the picket lines." Because we know that farmers/farm workers do not receive formal acting training, we can infer that Valdez believed that the actors he used did not require acting training in order for his plays to be effective. Thus, we can select (D).
Does this make sense? Let us know if you have any other questions!
