Which of the following actions is critical immediately after a power loss in the aircraft?

Immediately after a power loss in an aircraft, checking pilot communications is crucial because maintaining communication between the flight crew and air traffic control or ground control is vital for safety. In the event of a power outage, there may be emergency procedures that need to be communicated, as well as a need for situational awareness regarding the aircraft's status and intentions. Ensuring that the pilots have effective communication allows them to receive instructions, report their condition, and coordinate recovery efforts if necessary.

Restoring power to systems, ensuring cabin lights are operational, and notifying ground control are important, but they may come after verifying that communication lines are functioning. Without reliable communication, other actions may not be effectively coordinated, making it imperative to address communication first.