Answer:
A documentary is a film based on facts in which the maker tries to portray an aspect of reality, such as politics, science, society or history, nature or the personal perception of the documentary maker.
Documentaries are informative in nature. Sometimes documentaries attempt to provide an objective picture of a subject. There is a lot of debate about what is objective, because the documentary maker chooses his images from reality, which is in itself a subjective act. In a creative author's documentary, the emphasis is on the subjective vision of the filmmaker.
Therefore, the documentary maker will select the events to include in the documentary according to the approach he or she wants to give to it, be it objective or subjective.