A flare (or arresting of the sink rate) can't be initiated before the threshold (or start of overrun area or displaced threshold) because of any protruding equipment (say light poles). That's why they included option c) as a trick answer.
If the high sink-rate flare were to start at the same height and take the same duration as a normal flare, then the rapid increase in pitch would increase the angle-of-attack considerably and risk (or even cause) a stall.
So the flare needs to be more gradual and to start higher, eating up more runway.
(YouTube) Vref is normal during this ~6° steep approach test / technique demonstration.
You can watch an A318 flying steep approachs from multiple angles including the cockpit from the link above.
Custom automated call-outs are installed. See how high the callout "Standby, Standby, Flare," is commanded. Do note the overrun area at London City (first landing in the video), if it weren't there the landing would have been much longer.