What must an apprentice do upon returning from a leave of absence?

An apprentice in California must return their certificate and report their resumption to the bureau upon returning from a leave of absence. This requirement ensures that the bureau is informed of the apprentice's status and can verify their active participation in the apprenticeship program. Returning the certificate serves as a formal acknowledgment of their return to the program and allows for proper documentation in line with the regulatory requirements. This process is crucial for maintaining the integrity of the apprenticeship and ensuring that all records are up-to-date for training and compliance purposes.

The other options do not align with the specific regulations surrounding apprentice leaves. Notifying the bureau within a certain timeframe may not capture the necessary actions required for resuming apprenticeship, and filing for a new apprenticeship or completing a new application are unnecessary steps since returning from a leave does not equate to ending the apprenticeship.