What Is the Best Reason to Expect That Observer Reports

What is the best reason to expect that observer reports of personality could in some cases be more valid than self-reports would be?

A) Observers will see the person's behavior in only a limited range of settings,which makes it easier to provide accurate reports.
B) Observers are not necessarily aware of the person's thoughts and feelings,which makes it easier to provide accurate reports.
C) Observers might have a more objective perspective on the person's personality than he or she does,which makes it easier to provide accurate reports.
D) Observers can compare the person with other people,which makes it easier to provide accurate reports.
E) None of the above