Cheerleading is the fastest growing girls' sport，yet more than half of Americans do not believe it is a sport．Actually，competitive cheerleading is a sport．
A sport is a “physical activity against/with an opponent，governed by rules and conditions under which a winner is declared，and the primary purpose of the competition is a comparison of the relative skills of the participants．"Because cheerleading follows these guidelines，it is a sport．
Competitive cheerleading includes lots of physical activities．Like gymnasts，cheerleaders must  learn  to  tumble  (翻滚) ．They perform lifts and tosses．This is where the "flied' are thrown in the air，held by "bases" in different positions that require strength and cooperation with other teammates．
Just as basketball and football have guidelines for competitive play，so does competitive cheerleading．The whole routine has to be completed in less than 3 minutes and 15 seconds and the cheerleaders are required to stay within a certain area．
Competitive cheerleaders' goal is to be the best．Just like gymnasts，they are awarded points for difficulty，creativity and sharpness．The more difficult a mount，the sharper the motions，the better the score．Cheerleading is a team sport so without cooperation，first place is out of reach．
Cheerleading is the number-one cause of serious sports injuries to women．Emergency room visits for cheerleading are five times the number of those for any other sport，partially because they do not wear protective gear．While many athletes are equipped with hip pads or helmets，smiling cheerleaders are tossed into the air and spiral down into the arms of trusted teammates．The fliersmust remain tight at all times so that their bases can catch them safely．Also，because cheerleading is not yet recognized as a sport by many schools，neither proper matting nor high enough ceilings are provided to ensure safety．Instead，the girls use whatever space is available．More recognition of competitive cheerleading as a sport would decrease the number of injuries．
So why do many Americans not think cheerleading is a sport？Some people argue that cheerleaders are just "flirts in skirts" with their only job to entertain the crowd，but cheerleaders today work just as hard as other athletes．
Hopefully，cheerleading will become as well-known a sport as football and basketball，and even appear in the Olympics since cheerleaders are just as athletic and physically fit as those involved in the more accepted sports．
What does the underlined word "bases" in Paragraph 3 refer to？

A．Strength and cooperation

B．Lifts and tosses

C．Supporting teammates

D．Physical activities

Gymnasts are mentioned in the passage to _________

A．explain the dangers of cheerleading

B．show their similarities with cheerleaders

C．suggest cheerleaders learn to do gymnastics

D．present the guidelines of gymnastic movements

It can be leamed from the passage that cheerleading _________

A．is a good sport for all people

B．lacks necessary guidelines to follow

C．is more than a form of entertainment

D．enjoys greater popularity than other sports

This passage is written mainly to _________

A．attract more girls to cheerleading

B．draw people's attention to cheerleading

C．call for more recognition of competitive cheerleading as a sport

D．criticize some Americans who do not think cheerleading as a sport