An example of biased reporting is the one in letter D: A reporter includes his or her opinion in a story. In all the other alternatives, we can only see things a reporter must do in order to better illustrate, explain and inform. On the other hand, in letter D we see an example of prejudiced, partial reporting, since the reporter expresses his opinion on a certain story. All human beings are a set of beliefs (not only religion-wise) and whenever one expresses his/her opinions, those beliefs are included, sometimes explicitly, sometimes in a subtle way. Therefore, if a reporter includes his or her opinion in a story, the whole purpose of reporting will be strongly affected and facts can be hugely distorted.
