The aircraft does not need electrical power to board passengers if which three criteria are met?

The correct answer highlights three essential conditions under which boarding can take place without the need for electrical power.

Having sufficient light to board ensures that both the crew and passengers can safely navigate the cabin and aisles during the boarding process. Dim or no lighting could pose hazards, making it difficult for passengers to find their seats or for the crew to assist them.

A comfortable climate or temperature in the cabin is crucial for passenger comfort. Extreme temperatures can cause discomfort or distress among passengers, which might lead to safety concerns or issues during boarding. If the cabin environment is stable and pleasant, passengers are more likely to board efficiently and without issues.

Departure being imminent emphasizes the urgency of boarding under these conditions. If the flight is about to depart, it's essential to expedite the boarding process, and the normal reliance on electrical systems (like lighting or air conditioning) can be temporarily overlooked given these favorable conditions.

The other options do not align fully with the underlying principles and safety considerations required for boarding without electrical power. For instance, options regarding the state of the engines, weather conditions, or the readiness of the crew, while important for overall operations, do not independently support the boarding process without electrical systems.