The short wavelength limit ($\lambda_{min}$), also known as the cutoff wavelength, for X-rays produced in a tube is determined by the maximum energy of the incident electrons. The entire kinetic energy ($K = eV$) of an electron is converted into a single photon of maximum energy ($E_{max} = h\nu_{max}$). Using the relation $E = \frac{hc}{\lambda}$, we get: $eV = \frac{hc}{\lambda_{min}}$ $\lambda_{min} = \frac{hc}{e} \cdot \frac{1}{V}$

Since $h$, $c$, and $e$ are constants (Source ), $\lambda_{min}$ is inversely proportional to the accelerating potential $V$ ($\lambda_{min} \propto 1/V$). The graph representing this inverse relationship is a rectangular hyperbola. Assuming standard graphical representations where curve C depicts a hyperbola (decreasing $\lambda$ as $V$ increases), C is the correct representation.