Which of the Following Best Explains Why It Is Difficult

Which of the following best explains why it is difficult to evaluate the effectiveness of public relations campaigns?

A) Public relations campaigns do not have measurable objectives.
B) The effects of many public relations activities are difficult to separate from the effects of other marketing communications activities happening at the same time.
C) Marketing experts typically do not see the value in measuring the results of public relations activities.
D) Although outcome can be easily identified, output is difficult to quantify.
E) Public relations campaigns rely upon uncontrolled media.