Errol Morris's documentaries Gates of Heaven and The Thin Blue Line

A. are notable for their ambiguity of attitudes and intentions.
B. are chiefly valuable because of their clear, undisguised theses.
C. cannot be considered "constructed" documentaries because they provide little or no useful information about the past.
D. do not pretend to be antithetical and have thus had a powerful effect on real-world problems.

Answer: A