Which of these is a variant of motorsport road racing with open-wheel, known as shifter karts?

Kart racing or karting is a variant of motorsport road racing with open-wheel, four-wheeled vehicles known as go-karts or shifter karts. They are usually raced on scaled-down circuits, although some professional kart races are also held on full-size motorsport circuits. Karting is commonly perceived as the stepping stone to the higher ranks of motorsports, with former Formula One champions such as Sebastian Vettel, Nico Rosberg, Ayrton Senna, Lewis Hamilton, Michael Schumacher and Fernando Alonso having begun their careers in karting.

Karts vary widely in speed and some (known as superkarts) can reach speeds exceeding 161 kilometers per hour (100 mph), while recreational go-karts intended for the general public may be limited to lower speeds.