Exception reports

Question: gordon works in the accounts department of a retail business. He and his colleagues are looking at the sales figures for various types of clothing. The director asks them to use exception reporting to summarize their findings. Which of the following correctly defines the concept of exception reporting within a business context?
a) The reporting of unusual events, outside the normal course of events
b) The analysis of those items where performance differs significantly from standard or budget
c) The preparation of reports or routine matters on an ad hoc basis
d) The scrutiny of all data as a matter of course, save in exceptional circumstances.
In the above question, I think option a) is correct because the word exception seems related to unusual events. Also why the correct answer is really the correct and why are others wrong.