The standard emf for the cell cell reaction ` Zn + Cu^(2+) rarr Zn^(2+) + Cu ` is 1.10 volt at ` 25^@ C`. The emf for the cell reaction when ` 0.1 M Cu^(2+)` and ` 0.1 M ZN^(2+)` solutions are used at `25^@ =C` is .
A. `1.10` volt
B. 0.110 volt
C. `-1.10` volt
D. `-0.110` volt