What is the bandwidth if the start frequency is 6 MHz and the end frequency is 18 MHz?

To determine the bandwidth between two frequencies, you subtract the start frequency from the end frequency. In this case, the start frequency is 6 MHz and the end frequency is 18 MHz.

Calculating the bandwidth:

18 MHz - 6 MHz = 12 MHz.

Thus, the correct answer for the bandwidth is 12 MHz. This reflects the total range of frequencies from the lower end to the upper end, showing how effectively the frequencies can be utilized for communication or other applications within that range.

The other options represent values that do not accurately reflect the difference between the given start and end frequencies.