Darwin,a College Student,leased a Flat for 15 Months That Was

Darwin,a college student,leased a flat for 15 months that was to terminate in December 2009.Meanwhile,he had to go to New Jersey for a project,so he sublet his flat to a friend.Under these circumstances:

A) Darwin is not liable to the original owner anymore.
B) Darwin has not transferred his remaining rights to his friend.
C) Darwin has performed an illegal act.
D) Darwin has actually performed an assignment.