You may include examples, experiences, and theories. 

Note: a paragraph is a writing structure that requires a minimum of five complete sentences.
These five or more sentences should represent a valid knowledge of the topic.
It is not only about the number of sentences, but the valid knowledge of the topic represented through out the paragraph (Discussion) and/or the three sentences (Comment or Reply). And we are talking about “university student’s sentences” not “Mary is a girl or Tom is a boy” kind of sentences…