Final answer:
Option (B), According to OSHA regulations, an employer must maintain each canceled entry permit for at least 1 year.
Step-by-step explanation:
The question relates to the duration for which an employer is required by regulations to maintain each canceled entry permit within a workplace setting, likely within a confined space or a similar environment.
The Occupational Safety and Health Administration (OSHA) stipulates that the employer must maintain each canceled entry permit for at least 1 year. After this period, employers may dispose of the permits, but during that year, the permits can serve as a vital part of safety audits and compliance checks, ensuring that all entry operations complied with safety standards.