Which of the following is least indicative of fraudulent activity?

1. Numerous cash refunds have been made to different people at the same post office box address.
2. Three people were absent the day the auditors handed out the paychecks and have not picked them up four weeks later.
3. Internal auditors cannot locate several credit memos to support reductions of customers balances.
4. Bank reconciliation has no outstanding checks or deposits older than 15 days.