How can conducted and radiated noise caused by an automobile alternator be suppressed?

  1. By installing filter capacitors in series with the DC power lead and a blocking capacitor in the field lead
  2. By installing a noise suppression resistor and a blocking capacitor in both leads
  3. By installing a high-pass filter in series with the radio's power lead and a low-pass filter in parallel with the field lead
  4. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads