Final answer:
On official travel, the benefit that one can keep is unused per diem which is the excess amount from the fixed daily allowance after actual expenses have been deducted.
Step-by-step explanation:
While on official travel, an example of a benefit that you may keep is a) Unused per diem. Per diem is a fixed amount of reimbursement allotted for daily expenses such as meals, lodging, and incidental expenses while traveling for work. If your actual expenses are less than the per diem rate, the remaining amount is considered a benefit that you can keep. On the other hand, unauthorized expenses, lost receipts, or taking unapproved leave are not typically benefits that one can retain since they either lack proper authorization or evidence of expenditure, or they violate travel policies.