Note: The question asks what fuel is on board at the destination alternate. We can determine that a diversion has already been performed and so alternate fuel has been used.

Looking at the answer options:

Block Fuel - Taxi Fuel - Trip Fuel --> INCORRECT. This could reflect fuel at the destination, but not it's alternate.

Block Fuel - Trip Fuel - Final Reserve Fuel --> INCORRECT. No mention of taxi or alternate fuel being used. Also the final reserve should still be in the tanks.

Final Reserve Fuel + Contingency Fuel + Alternate Fuel --> INCORRECT. The alternate fuel would have been used already.

Final Reserve Fuel + Contingency Fuel + Extra Fuel + any Discretionary Fuel --> CORRECT. Each of these fuels could be on board when landing at the destination alternate. 

• Extra fuel, include anticipated delays or specific operational constraints that can be predicted
• Discretionary fuel, include a quantity at the sole discretion of the commander