C

In a circuit, the terminal potential difference across a cell is given by the equation:
$$ V = \varepsilon - i r $$
where:
- $V$ is the terminal potential difference,
- $\varepsilon$ is the emf of the cell,
- $i$ is the current flowing through the circuit,
- $r$ is the internal resistance of the cell.
If there is no current flowing (as in option C), then $i = 0$, making the terminal potential difference equal to the emf, $V = \varepsilon$. Therefore, it's not possible for the terminal potential difference to exceed the emf in this scenario.
For options A, B, and D, there is current flowing in the circuit. Thus, $V$ will be less than $\varepsilon$. Hence, the only configuration where $V$ could potentially exceed $\varepsilon$ would hypothetically occur with some conditions not shown in these diagrams. Based on the provided images, option C represents the scenario where current is not flowing and thus aligns with the question.
Therefore, the answer is C.