Which of the following is a valid statement about the use of visual observations during an audit engagement?
1. Visual observations can be used to detect ineffective controls, idle resources, and safety hazards.
2. Visual observations can be used during both preliminary survey and fieldwork stages of the audit engagement.
3. Visual observations can provide unsubstantiated facts to management if the internal auditor believes the information is useful.
4. Visual observations can assist an auditor in determining if a material observation should be communicated through informal means to the organization's senior management.