What should you do if you drive a tractor with a trailer on a slippery surface?

In the photo, a blue tractor with a red two-axle trailer is standing in a yard. When you drive such a combination on a slippery surface, you engage the front-wheel drive if the tractor has it - answer A.

After the front-wheel drive is engaged, the driving force is spread over four wheels, so each of them transfers less force and wheel spin is less likely. This improves traction when moving off and on climbs, and engine braking then works on both axles, which reduces the risk of the rear sliding out. Field and creeper gears (answer B) are for work in the field at very low speed - on the road they do not improve grip and only slow traffic down. Moving the load towards the back of the trailer (answer C) does not help the drive, and with a single-axle trailer it reduces the pressure on the tractor's rear axle and worsens traction; the load should be spread evenly. On a slippery surface you drive more slowly, turn gently and change down earlier.

Legal basis: Art. 19 para. 1 and Art. 61 para. 2 point 2 and 3 of the Road Traffic Act (Prawo o ruchu drogowym)