Several ways you can determine the validity is
1.) The author and his credentials.
2.) Sources that back up the article/publication.
3.) Whether the article features bias or none, when appropriate.
C, the group was founded and worked in Greece.
A simile is a comparison of two unlike things using "like" or "as".
For example:
"John was like an eagle, as he quickly spotted the rabbit, and was able to capture it."
Note that the word <em>like</em> was used, and that it compared <em>John</em> with the <em>eagle</em>
hope this helps