ANS:D - all of the above

Troubleshooting means is checking the every components are working properly or not. First, take the example of anything. First, if you want to check then first you need one input signal that is nothing but a pulse. Pulser is a device which generates the signals. Now you have to connect pulse to your circuit to give input then you need a logic probe. It's nothing but wire used to connect to devices. After that we have to check our output so we need oscilloscope which shows the output waveform on display. That's it.