The correct answer is B. The reader is meant to feel the tension of the conflict immediately.
Step-by-step explanation:
The term "In media res" is used to refer to a narrative opening or work such as a poem or novel that begins in the middle of the plot, usually in the most important moment of the conflict. This means the reader knows first what is the conflict and later discovers how this conflict emerged and how it is finally solved. Because of this "In media res" narrative uses flashbacks and other literary resources to tell the reader the background of the conflict and different to the traditional narrative the first element the reader has contact with is not the background or the character but the conflict itself. Thus it can be concluded the effect an in media res opening has on the reader is that the reader is exposed immediately to the conflict and because of this the reader feels immediately the tension of it.