Thevenin and Norton theorems

Consider the following circuit: 

The Thévenin equivalent resistance ($$Omega$$) at Points A-B is most nearly:

A.   8
B.   12
C.   20
D.   26

The Norton equivalent resistance ($$Omega$$) at Terminals A-B is most nearly: 

A.   50
B.   60
C.   100
D.   120