Final answer:
The Changes Log is the tool that contains a record of all actions performed in OPERA Cloud, allowing users to research the details of specific actions.
Step-by-step explanation:
The subject of this question is Computers and Technology and the grade level is High School. The tool that contains a record of all actions performed in OPERA Cloud is the Changes Log. With the Changes Log, a user can research the details of what actions occurred on a specific profile, reservation, or financial transaction.