One beaker contains 0.15 M Cd(NO3)2 and a Cd metal electrode. The other beaker contains 0.20 M AgNO3 and a Ag metal electrode. The notation of the cell is 
(-)Cd (s) | Cd2+ (aq, 0.15 M) || Ag+ (aq, 0.20 M) | Ag (s) (+) A.
(+)Cd (s) | Cd2+ (aq, 0.15 M) || Ag+ (aq, 0.20 M) | Ag (s) (-) B.
(-)Ag+ (aq, 0.20 M) | Ag (s) ||  Cd (s) | Cd2+ (aq, 0.15 M)(+) C.
(-)Cd (s) | Cd2+ (aq, 0.15 M) || Ag+ (aq, 0.20 M) | Ag (s) (+) D.
（-）Ag (s)Ag+ |  (aq, 0.20 M) || Cd2+ (aq, 0.15 M)|  Cd (s) (+)