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In the given potentiometer circuit, the resistance of the potentiometer wire $AB$ is $R_0$. $C$ is a cell of internal resistance $r$. The galvanometer $G$ does not give zero deflection for any position of the jockey $J$. Which of the following cannot be a reason for this?
  • A$r > R_0$
  • B$R > > R_0$
  • C$\mathrm{emf}$ of $C > $ $\mathrm{emf}$ of $D$
  • DThe negative terminal of $C$ is connected to $A.$
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