D). Was a controversial exhibition of modern art.
Explanation:
The Armory show organized in 1913 remained one of the controversial exhibitions in the history of modern art. The exhibition was arranged by the group of American Painters as well as Sculptors to set the 'new' value for art and introduction of American artists into the European field of developments but the young American artists could not receive the limelight they were aspiring for. Thus, it created a huge controversy but remained significant as it aimed to provide American artists with their due respect. Therefore, option D is the correct answer.