A button cell used in watches functions as follows
$\underset{\left(\text{s}\right)}{\text{Zn}}+\underset{\left(\text{s}\right)}{{\text{Ag}}_2\text{O}}+{\text{H}}_2\text{O}\rightleftharpoons \underset{\left(\text{s}\right)}{2\text{Ag}}+\underset{\left(\text{aq}\right)}{{\text{Zn}}^{2+}}+2{\text{OH}}^{-}$
If half cell potentials are
$\underset{\left(\mathrm{a}\mathrm{q}\right)}{\mathrm{Z}{\mathrm{n}}^{2+}}+2{\mathrm{e}}^{-}\to \underset{\left(\mathrm{s}\right)}{\mathrm{Z}\mathrm{n}}$
$\mathrm{E}°=-0.76\mathrm{V}$
$\underset{\left(\mathrm{s}\right)}{{\text{Ag}}_2\text{O}}+\underset{\left(\mathrm{l}\right)}{{\text{H}}_2\text{O}}+2{\text{e}}^{-}\to \underset{\left(\mathrm{s}\right)}{2\text{Ag}}+2{\text{OH}}^{-}$
$\mathrm{E}°=0.34\mathrm{V}$
The cell potential will be

• Correct answer
  A

  1.1 V
• B

  0.42 V
• C

  0.84 V
• D

  1.34 V

Hence, the correct answer is option: 'A'.