Question

in this sport, racers need to go up and down ground that is flatter for long distances cross country skiing ski marathon ice skating ski jogging

Explanation:

The description mentions racers going up and down flatter ground for long distances, which matches Cross Country Skiing. Cross - country skiing involves traveling over relatively flat or gently rolling terrain over long distances, using ski poles for propulsion. Ski Marathon is a type of cross - country skiing event but the description is more general for the sport itself. Ice Skating is on ice and doesn't involve the same kind of ground movement as skiing. Ski Jogging is not a recognized standard skiing sport.

Answer:

Cross Country Skiing