What should a pilot do if directed to return to starting point by a flashing green light in flight?

When a pilot is directed to return to the starting point by a flashing green light while in flight, the appropriate action is to follow the instruction and return to land. The flashing green light signals to the pilot that they are being directed to return to the airport from which they departed.

This instruction serves as an important communication tool from air traffic control, indicating that the pilot should prioritize returning to land as directed rather than taking any alternative action. It's a critical response to ensure safety and compliance with air traffic control directives, especially in situations where a return may be necessary for safety reasons or external factors such as weather or equipment issues.

Other choices do not accurately reflect the intended response to a flashing green light. For instance, merely proceeding to land or descending immediately does not imply the urgency or requirement to return to the starting point, making those options less appropriate in this specific context.