Final answer:
The auditor should have interviewed management for additional information because the interview technique provides the opportunity to probe promising areas and gain a deeper understanding of the control questionnaire responses.
Step-by-step explanation:
The auditor should have interviewed management for additional information because the interview technique provides the opportunity to insert questions to probe promising areas. By conducting interviews with management, the auditor can gather more detailed information and gain a deeper understanding of the control questionnaire responses. Additionally, interviews allow for a more interactive and flexible approach to obtaining information, compared to other audit techniques.