Most young people enjoy some form of physical activity. It may be walking, cycling, swimming or in winter, skating or skiing. It may be a game of some forms - football, basketball, hockey, golf of tennis. It may be mountaineering. Those who have a  _ for climbing high and difficult mountains are often looked up with astonishment. Why are men and women willing to suffer cold and hardship, and to take risks in high mountains? This astonishment is caused, probably, by the difference between mountaineering and other forms of activity to which men give their leisure . Mountaineering is a sport and not a game. There are no man - made rules, as there are for such games as golf and football. There are, of course, rules of different kind which it would be dangerous to ignore, but it is this freedom from man - made rules that makes mountaineering attractive to any people. Those who climb mountains are free to use their own methods, but the sport requires high mental and physical qualities. A mountain climber continues to improve in skill year after year. A skier is probably past his best by the age of thirty, and most international tennis champions are in their early twenties. But it is not unusual for men of fifty or sixty to climb the highest mountains in the Alps. They may take more time than younger men, but they certainly experience equal enjoyment. Mountaineering is a sport, not a game because   _  .
it has man-made rules it is too dangerous for climbers it can't bring people joy and leisure it is free for climbers to use their own methods.