The correct answer is: B. Some conspiracy theorists believe the United States moon landing was a propagandist hoax.
This sentece uses the most specialized language, suitable for an academic paper. When writting in an academic context everything has to be clear, there is no space for ambiguous terms as they can lead to confussion, taking away your credibility. The important ideas must be expressed with the correct words, remeber that there are words for almost anything you want to say. In this case the use of "conspiracy theorists" and "propagandist hoax" give some backgroumd information of what you're talking about as these words represent some topic that has been developed. They state some characteristics and factors that will guide te audience to a better undestanding.
The other options use colloquial language, not suitable for an academic paper as it can be vague and too simple.