The speed $v$ of waves in deep water is related by the equation $v^2 = \frac{g\lambda}{2\pi}$ where $\lambda$ represents the wavelength of the waves and $g$ represents the acceleration of free fall. A student measures the wavelength $\lambda$ and the frequency $f$ for a number of these waves. Which graph should he plot so that the graph is a straight line through the origin?
- A$f^2$ against $\lambda$
- B$f$ against $\lambda^2$
- C$f$ against $\frac{1}{\lambda}$
- D$f^2$ against $\frac{1}{\lambda}$