【正确答案】 C

【答案解析】[解析] 17-20
In the early 1960s, Wilt Chamberlain was one of the only three players in the NBA listed at over seven feet. If he had played last season, however, he would have been one of 42. The bodies playing major professional sports have changed dramatically over the years.
However, Americans have generally stopped growing. Though typically about two inches taller now than 14:0 years ago, today's people apparently reached their limit in the early 1960s. And they aren't likely to get any taller. "In the general population today, at this genetic and environmental level, we've pretty much gone as far as we can go," says expert William Cameron Chumlea of Wright State University. In the case of NBA players, their increase in height appears to result from the increasingly common practice of taking on players from all over the world.
Growth demands calories and nutrients. At the start of the 20th century, under—nutrition and childhood infections got in the way. But as diet and health improved, children have, on average, increased in height by about an inch and a half every 20 years, a pattern known as the trend in height. Yet average height hasn't really changed since 1960.
There are some real limits that are set by the genetic architecture of the individual organism. During childbirth, larger babies have more difficulty passing through the birth canal. Moreover, even though humans have been upright for millions of years, our feet and back continue to struggle with keeping this pose and cannot easily stand repeated strain imposed by oversize limbs.
Genetic maximums can change, but don't expect this to happen soon. Experts ensure that 90 percent of the uniforms and workstations fit recruits without alteration. They say that, unlike those for basketball, the length of military uniforms has not changed for some time.