Read the excerpt from "The Role of Social Media in the Arab Uprisings" by Heather Brown, Emily Guskin, and Amy Mitchell. Almost immediately after the Arab uprisings began, there was debate over the role and influence of social media in the ouster of Tunisian president Zine El Abidine Ben Ali and the imminent overthrow of [Egyptian president Hosni] Mubarak. In covering what some deemed the Facebook or Twitter revolutions, the media focused heavily on young protesters mobilizing in the streets in political opposition, smartphones in hand. And since then, the violent and sectarian unrest in Syria has brought increased attention to the role of citizen journalism. Social media indeed played a part in the Arab uprisings. Networks formed online were crucial in organizing a core group of activists, specifically in Egypt. . . . Additionally, digital media has been used by Arabs to exercise freedom of speech and as a space for civic engagement. What type of evidence do the authors use in this excerpt?