What action should be taken after applying changes in an Apex class before deployment?

After applying changes in an Apex class before deployment, it is essential to ensure that any scheduled jobs are managed properly in the environment where the changes will be deployed. Unscheduling Apex jobs is crucial because, if changes are made to the Apex class that a scheduled job depends on, it could lead to unexpected behaviors or failures upon execution of that job in the target environment. By unscheduling those jobs beforehand, you maintain system integrity and avoid complications that might arise from conflicting changes.

The other options, while they may seem relevant, do not directly address the immediate necessity of managing scheduled jobs before deployment. Assigning permission sets, deleting records, or checking for compilation errors can be handled either after deployment or are part of a different aspect of deployment preparation and management, thus making them less critical in the context of immediate actions needed post-change application.