What is the fuel requirement if a second alternate is required?

When a second alternate is required, the fuel requirement includes multiple components to ensure the aircraft can reach alternate airports if necessary. The correct answer reflects the need to have fuel for the flight to the intended destination, enough to reach the furthest alternate airport, and additional fuel to hold for an additional 45 minutes at cruising speed.

This requirement ensures the safety of the flight, as it prepares for possible contingencies such as bad weather or other issues that might prevent landing at the primary destination or even the first alternate. The inclusion of the 45-minute holding fuel accounts for any delays that might occur during the approach and landing phases, providing an extra safety margin. Hence, this comprehensive planning is crucial for maintaining flight safety and operational integrity when a second alternate is in consideration.

In contrast, the other answers do not adequately address the need for safety and contingency planning that is part of the aviation fuel requirements under these circumstances.