A liquid having coefficient of cubical expansion ' $\gamma$ ' is kept in a copper vessel having coefficient of linear expansion $\frac{\gamma}{3}$. If heat is supplied to the vessel, the original level of the liquid in the vessel will

The coefficient of cubical expansion of the liquid is $\gamma_L = \gamma$, while the vessel's coefficient of linear expansion is $\alpha_V = \frac{\gamma}{3}$.
The cubical expansion coefficient for the vessel becomes $\gamma_V = 3\alpha_V = 3\left(\frac{\gamma}{3}\right) = \gamma$.

Given equal initial volumes $V_0$ and temperature change $\Delta T$,
the liquid expands by $\Delta V_L = V_0 \gamma \Delta T$ and the vessel's internal volume by $\Delta V_V = V_0 \gamma \Delta T$,
resulting in zero apparent volume change: $\Delta V_\text{app} = V_0(\gamma - \gamma)\Delta T = 0$.

The liquid level remains constant: $\boxed{C}$.