What is the approximate length of the driven element of a Yagi antenna for 14.0 MHz?

The driven element of a Yagi antenna acts fundamentally as a half-wave dipole. To find the approximate length of a half-wave dipole in metres, you can use the standard formula: 143 divided by the frequency in MHz. Using this formula for 14.0 MHz, the calculation is 143 / 14.0 = 10.21 metres. This gives the physical length of the driven element required for it to be resonant at that specific frequency. Other options provided are either full wavelength calculations or calculations for entirely different frequencies, making 10.21 metres the only mathematically sound choice for a half-wave element at 14.0 MHz.