Question

The BEST example of a primary source is
a. an article about the Battle of the Alamo by a history professor.
b. a Wikipedia article about the Texas Revolution.
c. the diary of the commanding officer's aide.
d. a website run by Texas Revolution reenactors.

Answer 1

C. the diary of the commanding officer because the source is from when the event occurred whereas the other sources are after the fact.  

Answer 2

I believe that the best example of a primary source would be C 
I hope that helps at least a little :)