The correct answer is C. In reality
In the phrase of the question "While it may seem like psychiatrists help people 'get away with murder or other violent crimes, in reality, they play an important role in the criminal trial process" someone is describing a problematic situation, and wants to persuade the receptor to change that preconception using the phrase "in reality" that is a way to support an idea and give it reliability because it is a way used by the author to convince the listener and make him/her believe that he is knowledgeable to that situation. So, the correct answer is C. In reality.