A flare (or arresting of the sink rate) can't be initiated before the 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 take the same duration as a normal flare, the sudden increase in pitch would increase the AoA considerably and risk (or even cause) a stall.

So the flare needs to be more gradual and to start higher, eating up more runway.

[![enter image description here][1]][1]<BR>Vref is normal during this steep approach test / technique demonstration (video link below).

You can watch a BA A318 flying a steep approach into London City from multiple angles including the cockpit [here][2] (YouTube), with custom automated call-outs. See how high the callout "*Standby, Standby, Flare, Flare*" is commanded. Do note the overrun area, if it weren't there the landing would have been much longer.


  [1]: https://i.sstatic.net/ZnuFa.png
  [2]: https://www.youtube.com/watch?v=XDWKheHMDYs