Murphy wants to use the biography Mockingbird: A Portrait of Harper Lee as a source for his research paper on Harper Lee. How should this source be classified on his bibliography?
A. as a secondary source because it provides a commentary on Harper Lee
B. as a primary source because it is about the life of writer Harper Lee
C. as a secondary source because it is based on Harper Lee's fictional novel
D. as a primary source because it was written about Lee during her lifetime