A) All of these choices are correct
- The repeater receiver requires audio tone burst for access
- The repeater receiver requires a CTCSS tone for access
- The repeater receiver may require a DCS tone sequence for access
It is quite common for repeaters to require the use of a specific sub-audible tone to open the repeater's receiver squelch. This helps reduce inteference. You can find the specific tone for the repeater contacting the repeater's owners or by using a repeater directory. The ARRL publishes an updated paper bound and electronic repeater directory each year.
Written by: NJ2X, Michael Maher