If the braking distance of the motorcycle you are riding at the speed of 30 km/h is 6 metres, increasing the speed to 60 km/h will result in:

This question is about how braking distance depends on speed. If at 30 km/h the braking distance is about 6 m, then after increasing the speed to 60 km/h it will become longer, about 24 m - answer B.

The Road Traffic Act requires you to ride at a speed that ensures control of the vehicle, and braking distance is the best argument for this rule. It depends on the energy of motion, and this grows with the square of the speed: twice the speed means four times more energy, which the brakes must turn into heat. Six metres times four gives 24 m. Answer A (12 m) wrongly assumes that the distance grows in proportion to the speed, and answer C (36 m) is six times the distance without any justification. On top of the braking distance, there is also the distance travelled during the reaction time - at 60 km/h that is about 17 m per second - so the actual stopping distance from 60 km/h is more than 40 m. On a motorcycle this matters twice as much, because braking too hard in panic locks the wheel and ends in a fall before you even reach the obstacle.

Legal basis: Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)