How Have Narrative Feature Films Incorporated into Themselves Documentary Filmmaking

How have narrative feature films incorporated into themselves documentary filmmaking techniques?

A) by using small crews, natural lighting, handheld cameras, and nonprofessional actors
B) by tackling issues of political and social importance
C) by being informed by painstaking research
D) by interrupting the narrative flow with interviews of experts in the field that the film is examining
E) by being made with extremely small budgets