What are auto decertifications primarily attributed to?

Auto decertifications are primarily attributed to the failure to re-certify past the 90-day expiration date. This means that if a crew member's certification expires and they do not complete the re-certification process within 90 days, their status will automatically be changed to 'decertified'. This system is put in place to ensure that all crew members maintain their qualifications and are up-to-date with current standards and practices.

Options related to training completion, safety guideline maintenance, and licensing of all crew members do not directly lead to auto decertification. Rather, they pertain to the broader aspects of qualifications and operational standards that support the overall effectiveness and safety of the operations, but do not result in automatic decertification if not met. The specific focus on the 90-day expiration for re-certification is what makes this answer correct in the context of understanding the rules governing certification status.