This is an example of imitation/copying.
Imitation is a way of behavior where an individual<em> observes and replicates the behavior of others.</em> It is a reproduction of an act that is simulated by the perception of a similar act by another animal or person.
To imitate/copy somebody or something a model is needed. The copying may be done none-consciously ( seeing and copying others without thinking about the reason to do it ,) or it can be a conscious strategy ( out of uncertainty how to act or behave in some situation).
In Libby's case, the act of imitation<em> comes as a conscious process of wanting to behave correctly</em> and to fit in with others.The other students are Libby's model to copy her behavior from.
Answer: For America, the gun is a story of innovation, power, violence, character, and freedom. ... From Samuel Colt's early entrepreneurism to the successful firearms technology that helped make the United States a superpower, the gun is inextricably tied to our exceptional rise.
Explanation:
I believe the answer is: a. to enhance credibility
Personal experience would give the readers with a certain level of assurance that the writers at least know what they are talking about.
For example, let's say that there are two authors of a self defense book. The first author has an experience as a president's bodyguard while the second author is a full time web designer. Most people would most likely see the first author as the more credible one.