Which of these atmospheric factors reduces the possibility of skidding?

The question is about driving a tram and compares three weather conditions in terms of the risk of the wheels skidding on the rails. Of these, black ice gives the lowest risk of a tram skidding - answer A.

The reasoning of the question's authors is as follows: a heavy tram, with its weight, crushes the thin layer of ice on the rails, and the ice crystals that form work in a similar way to sand from the sander, which means they increase wheel grip. Drizzle (answer B) does not wash the rails clean, but mixes with dust and grease into a thin, slippery paste, and hail (answer C) covers the track with ice pellets - both conditions greatly reduce wheel grip. Note: this comparison applies only to a tram on rails. For a car, black ice is one of the most dangerous conditions, so do not transfer this answer to other categories. Even in a tram, drive more slowly on black ice and brake earlier and gently.

Legal basis: tram driving permit training programme: Regulation of the Minister of Transport, Construction and Maritime Economy of 13 July 2012 on the training of persons applying for driving entitlements, instructors and lecturers (Dz.U. 2012 poz. 1019, repealed), Annex No. 1 part II point 2.2.3 item 6 "Skidding - causes and prevention"; Art. 19 para. 1 of the Road Traffic Act (Prawo o ruchu drogowym)