Explanation:

- The blank needs a word that describes types of expenses involved in a trip.

- Overhead: Refers to ongoing business expenses not directly attributed to creating a product or service. In travel, it includes costs like administration, insurance, etc.

- Overdone: Not related to expenses. Typically means something is excessive or beyond the necessary amount.

- Overburdened: Means excessively loaded or weighed down. More often used in context of workload or stress.

- Overpaid: Refers to someone being compensated more than what is typically expected. Not relevant to expenses for a trip.