For a fixed-wing IFR flight with a RNAV approach and a TEMPO condition, what is true about alternate airport requirements?

In the context of IFR flight planning, particularly for RNAV approaches, the requirements for alternate airports can be influenced by specific weather conditions like TEMPO. When TEMPO conditions are in place, they refer to temporary weather situations that may meet certain criteria, potentially relaxing alternate airport requirements.

Under these circumstances, if an approach can be conducted and the weather conditions are expected to improve or remain within acceptable limits, it might not be necessary for the pilot to designate an alternate airport. This can occur when the destination and approach are forecasted to be above the minimums required for that approach right at the time of arrival.

Therefore, choosing not to designate an alternate can be justified if the pilot has evaluated the conditions and determined that, despite the TEMPO conditions, the flight can be safely conducted without the need for an additional alternate airport. This makes option B the correct choice as it reflects the guidelines provided by regulations regarding alternate airport requirements in specific scenarios like this one.