Which of the following best represents the notion that social identities are relational and comparative?
选项：

A: Medical students are perceived as doctors by patients in the hospital but as children by their parents.
B: Medical students are perceived as doctors by patients in the hospital but as students by their professorsIn the classroom.
C: Medical students are perceived as doctors by patients in the hospital but as students by themselves.
D: Medical students are perceived as students by patients in the hospital and as students by their professors in the classroom.
E: Medical students are perceived as students by patients in the hospital before they graduate, but as doctors by the same patients after they have graduated.