Why Was Mary Whiton Calkins Denied the Ph

Why was Mary Whiton Calkins denied the Ph.D. degree she had earned in her graduate studies of psychology at Harvard University?

A) Her research was in an area called comparative psychology that was not recognized as a legitimate part of scientific psychology at Harvard University at the time.
B) At the time, Harvard University forbade the use of nonhuman animals in psychology research.
C) William James was opposed to opening the field of psychology to women and refused to support her application, despite the fact that she was his most brilliant student.
D) She was a woman, and at the time Harvard was not a coeducational institution.