What type of evidence do the authors use in this excerpt?

a: historical examples of political changes

b: personal anecdotes about the impact of social media
research studies that

c: correlate politics and social media

d: social media posts about the arab spring

There isn't an excerpt to analyze.

Explanation:

Even though, it is possible to define each option:

Historical examples of political changes refers to past events that affected or changed politics in a country; sources like history books or historical archives are helpful for this.

Personal anecdotes about the impact of social media refers to what the author has seen or experienced related to social media and how it has affected the political events.

Research studies that correlate politics and social media are studies that analyze the relationship between the political events and how social media has impacted them.

Social media posts about the Arab Spring are sources like posts in websites like F.cebook or T.itter, where users can express their ideas related to the Arab Spring.

c, his tragic flaw to cause his downfall