Which of the following is a detective control?

 Verification of hash totals is a detective control. A detective control is a control that aims to identify and report errors or irregularities that have already occurred. Verification of hash totals is a technique that compares the hash values of data before and after transmission or processing to detect any changes or corruption. The other options are examples of other types of controls, such as programmed edit checks (preventive), backup procedures (recovery), and use of pass cards (preventive). References: CISA Review Manual, 27th Edition, page 223