根据短文内容，从每小题A、B、C三个选项中选出一个最佳答案。
Rock climbing (攀岩) did not become a sport until late in the 1900s. But now it has become a popular outdoor activity.
If you have ever done rock climbing, you will know that it is not an easy sport. Indoor and outdoor rock climbing both need practice. What most people don't know is that rock climbing is one of the sports that depend on your body and will (意志).
To climb successfully, one must use wonderful skills. One of the important rules is to always have three parts of your body on the rock face. Another important rule is that your arms only hold you close to the rock face while your legs are pushing you up. The closer you are to the rock face, the easier it is to climb.
Rock climbing is a wonderful sport. Once you start to learn how to climb, you'll find more fun. People who like games such as chess playing or problem-solving may love rock climbing, because they are nearly the same in the way of thinking. For anyone who wants to get into beautiful shape, rock climbing is a fun and good way. Anyone who enjoys a difficult game and loves the outdoors should think of taking rock climbing as a new hobby.
