Parkour is thought by many to be an extreme sport—especially when people see parkour practitioners (known as traceurs) climbing walls and jumping off buildings. However, it might be better to characterize parkour as a radical art form involving both the body and mind. Although this art form can be extreme, it does not involve the teamwork, structure, or competitiveness of organized sports. In addition, traceurs can be difficult to recognize, as they do not wear matching uniforms to identify themselves. Parkour and its practitioners are in a category of their own. The ultimate goal of parkour is for a person to mentally and physically prepare to overcome any obstacle he or she may face. Traceurs, who pit their bodies against various types of obstacles, often risk physical injury, and safety is an important concern. While practicing parkour, a traceur's route may take him or her over a large boulder, across several rooftops, or across the top of a wall. As dangerous as these acts may sound, most traceurs do attempt to learn the safest way to move, jump, and land. Parkour has become a popular art form in urban settings around the world due to the many obstacles located around the cityscape. This has led to concerns for traceurs' safety, as well as worries about traceurs trespassing on private property and attempting to jump from high buildings. As in most physical activities, safety for oneself and others should be paramount in the practice of parkour.
Which sentence best states the main idea of the first paragraph?
A.
Parkour is only dangerous when traceurs are not careful.
B.
Parkour does not have many practitioners around the world.
C.
Parkour is a reinvention of the classic form of extreme sports.
D.
Parkour does not have much in common with extreme sports.