Which of the Following Is the Most Obvious Reason for Using

Which of the following is the most obvious reason for using self-report?

A) Individuals have access to a wealth of information about themselves that is inaccessible to anyone else.
B) Observer bias is very difficult to remove from collected data.
C) The desire to portray oneself in a positive light is highly prevalent.
D) There is a negligible amount of bias in self-report data.