How Has the Creation of Reassortant Viruses Helped in the Study

How has the creation of reassortant viruses helped in the study of reoviruses?

A) It allows for the infection of new hosts via antigenic shift.
B) It allows for the association of a specific viral protein with its function.
C) It allows scientists to measure the size of the various genome segments.
D) It allows for easier identification of specific virion protein.
E) It allows for the creation of new gene therapy vectors.