Final answer:
The correct answer is option d. entry supervisor. The entry supervisor is responsible for authorizing and canceling entry permits for permit-required confined spaces, in accordance with OSHA regulations.
Step-by-step explanation:
The correct answer is option d. entry supervisor. In the context of permit-required confined spaces, the Occupational Safety and Health Administration (OSHA) specifies in regulation 29 CFR 1910.146 that the entry supervisor is responsible for determining if acceptable entry conditions are present at a permit-required confined space where entry is planned, for authorizing entry and overseeing entry operations, and for terminating entry as required by this section.
It is the entry supervisor's duty to sign the permit to authorize entry and to cancel the permit when the job is completed or if a condition arises that requires an evacuation of the space. Thus, the entry supervisor plays a critical role in ensuring the safety and compliance of confined space operations.