Additional fuel changed slightly during the 2022 regulation change, however, questions that remain to be asked about it must conform correctly to the original definition, however, this particular question is actually covered by both the old and new regulations, as this particular scenario is the only thing that remains a part of the “additional fuel” consideration

NEW REGULATIONS

AMC1 CAT.OP.MPA.181 Fuel/energy scheme - fuel/energy planning and in-flight re-planning policy — aeroplanes
Basic Fuel scheme
…(f) for additional fuel, include an amount of fuel that allows the aeroplane to proceed, in the event of an engine failure or loss of pressurisation, from the most critical point along the route to a fuel en route alternate (fuel ERA) aerodrome in the relevant aircraft configuration, hold there for 15 minutes at 1500 ft (450 m) above the aerodrome elevation in standard conditions, make an approach, and land;

Under the OLD REGULATIONS, the additional fuel was an amount of fuel which is only applicable to some operations and it can cater for the above, and a couple of other “what ifs” of a particular operation, including if no destination alternate was chosen (legally), 15 mins hold at 1500 ft would be added within additional fuel. That has now been moved to alternate fuel.

ADDITIONAL FUEL

Following loss of pressurisation, the drill will be to perform an emergency descent from cruise altitude down to 10 000 ft (potentially via a high terrain escape routing). Having completed the descent, the aircraft must divert and the fuel must be enough for this scenario. The fuel flow is always greater in this scenario due to the low altitude and airspeed.

In the event of an engine failure, the aircraft would be forced to descend to a lower altitude (potentially via a drift-down route over high ground) due to lack of thrust. This case could increase the fuel consumption in some cases, but is not the same as above as sometimes one-engine inoperative cruise can actually burn marginally less fuel, it's all dependent on the individual circumstance.

As a consequence, further uplifted fuel must be calculated during the pre-flight planning procedure, including fuel to descend as necessary, proceed to an adequate aerodrome, hold for 15 minutes at 1 500 ft and execute an approach/landing. This element of fuel would appear as Additional fuel on the flight plan, ensuring that sufficient fuel is carried for such an event.

As for the answer, we would say that this also means the fuel planning has been INCORRECTLY done, however feedback indicates that isn't present on the correct answer for some reason.