When writing about this, be sure to think of one particular person who said or did something that's always taught you a valuable lesson in life. 
        
             
        
        
        
Answer:
an or no article
Explanation:
the ans is between these two
 
        
             
        
        
        
Explanation:
I could not find the article that is missing in your question but I will tell you something more about the author's bias in the literature work so you can find it by yourself. 
-  Authors are not always having fair thinking about something, they also can have many mistakes in their thinking patterns or wrong choices. They can make it also on purpose or it could be just their natural thinking. 
A bias is representing those unfair presentations of some events or situations in literature. They are having their point of view that isn't always matching our expectations. If you want to find the author's bias in your article you must find first what is the way that he looks at certain situations or feelings.