What is referred to as the portion of a ticket that the travel agent keeps for their records?

The correct answer is the agent's coupon, which is the portion of a ticket that the travel agent retains for their records. This coupon serves multiple purposes, such as confirming the details of the transaction and serving as a reference in case any issues arise with the booking.

Travel agents often need to keep detailed records of customer transactions for accountability, financial tracking, and customer service purposes. The agent's coupon is specifically designed to facilitate this record-keeping process.

In contrast, the other options represent different elements in travel and tourism transactions. An agent's commission refers to the earnings a travel agent receives from the suppliers or services they sell, not a part of the ticket itself. A travel voucher is typically used as a form of payment or discount for future travel services and does not relate to the ticket structure. A reservation confirmation is a document that confirms a booking made by the traveler and does not pertain to the ticket portion that the agent retains.