A. The spread of the internet was the most important development of the 22st century
B. Over 3 billion people around the world used the internet as of 2015
C. The internet can be used to conduct business, catch up with friends, or read the news
D. Hackers sometimes illegally access personal and financial information stored on the internet
(A) The spread of the internet was the most important development of the 22st century
Option (A) is best to describe a thesis that can be debated since it is the author's belief that the internet is the most important development of recent centuries. Other people who disagree with this perspective can give an argument as to why they think some other findings or inventions are more important to humanity as a whole. The other topics are mostly explanatory essay topics (C) and (D), or subtopics of a larger thesis (B).