Which of the following actions may extend a provisional certification?

The action that may extend a provisional certification is waiting for the results of the exam. In the context of certification processes, a provisional certification is often granted to individuals who have met certain requirements but are still awaiting the completion of the final examination or assessment. During this period, if the individual is in a waiting status for exam results, their provisional certification may remain valid until those results are processed, as the certification is contingent upon the outcome of the exam.

The other actions listed do not inherently or directly relate to extending a provisional certification. Starting a new job typically does not impact the status of a certification; taking additional time off might affect job responsibilities but not the certification itself; and requesting a formal review is generally a process related to contesting or evaluating decisions rather than extending provisional status. Therefore, waiting for exam results is the correct action that may lead to an extension of provisional certification.