Crossing parallel roads

[4_blues]

Question: During a low level flight 2 parallel roads that are crossed at right angles by an aircraft. The time between these roads can be used to check the aircraft:

track
position
drift
groundspeed

Turns out correct answer is groundspeed. However, I would have assumed that in order to determine the groundspeed one would need to know how far apart the roads are and then by measuring the time it takes to fly the gap will determine the gs. Is this not correct?

I would have assumed that flying over two parallel roads I could tell the drift, assuming the roads had features along the sides such as bushes, lamposts, signs etc. Surely this is a 'more likely' scenario that crossing two roads and happening to know the distance apart?

Thanks

EDIT: Just noticed it says the time between these roads can be used and with the time giving me naff all idea of drift that would shoot my theory down?????

[paco]

The question is not asking you what your groundspeed is - just whether they can be used to check your groundspeed. The answer is yes, technically.