A technician is testing an undocumented digital system with a signature analyzer. What indications ...

A technician is testing an undocumented digital system with a signature analyzer. What indications should the technician look for?
 
  A) Look for similar signatures that show up at different points in the circuit; no two points should be the same.
  B) As signals flow from one circuit to another, changes will take place; look for changes in the signatures, especially between inputs and outputs.
  C) Without documented signatures, the instrument is basically useless.
  D) Use a logic analyzer to verify the correct operation of the signature analyzer; once its accuracy has been confirmed, its indications can be relied upon for troubleshooting.