When following the troubleshooting methodology, which of the following should be performed when establishing a theory of probable cause?

Questioning the obvious helps ensure that all potential causes, even simple ones, are considered and not overlooked when formulating an initial theory of what might be causing the problem.

Identifying symptoms is the initial step in the troubleshooting methodology, preceding the establishment of a theory of probable cause.

Duplicating the problem is typically done to test a theory of probable cause, not during the formulation of the theory itself.

Determining if anything has changed is part of gathering information and identifying symptoms, which occurs before establishing a theory of probable cause.