A guitar string of length L has a fundamental frequency. Where should it be pressed to produced another fundamental frequency, if the ratio of two fundamental frequencies is f?

• A

  $\frac{\mathrm{L}}{\mathrm{f}}$

• B

  fL

• C

  $\frac{1}{{\mathrm{f}}^2}$

• D

  $\frac{\mathrm{L}}{{\mathrm{f}}^{{\displaystyle \frac{1}{2}}}}$