Terry received a support call from a supervisor at his company. When he arrived at his supervisor's work area, Terry spoke with the supervisor and asked him for his help in finding a solution for his computer's problem. The supervisor showed Terry the error message and reproduced the error for him to see. Terry backed up all the important data on the machine. What is the next step Terry should take in the troubleshooting process?
a. Establish a plan of action to resolve the problem.
b. Document his findings.
c. Establish a theory of probable cause.
d. Test his theory.