Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
the current record, held by Algerian Noureddine Morceli, is 3:44 , more than 5 percent faster than Bannister's speed. What Iffley Road witnessed was just another step along the road to an ever quicker mile, part of the inexorable improvement of athletic performance that we usually take for granted, particularly when the Olympics roll around. If you stop to think about it, though, such constant progress is remarkable. After all, as biomechanical machines with a standard set of parts, humans should be subject to the same limitations we see in, say, automobiles. How come they aren't? A lot of entrepreneurs and technophiles would like us to think that the answer has to do with discoveries in the world of sports technology. A new Nike shoe is trumpeted as something that will shave at least one-thousandth of a second off your 100-meter time. Trainers measure the rate of buildup of lactic acid in your muscles, then claim that their programs will control it. Nutritionists fine-tune athletes' diets. Even the old sexual-abstinence-before-the-race dogma is being re-evaluated under the all-seeing eye of science. But I consider all this little more than tinkering. Sports records would continue to tumble even if training methods or athletic clothing or sexual practices were exactly the same today as they were in 1896, when the first modern Olympics took place. These minor miracles are the product neither of technology nor of training but of demographic patterns that affect us all. Over the past century, the human race has been affected by a slew of what demographers call "secular" trends. (In this context, "secular" does not refer to a trend's lack of spirituality but to its longevity: Secular trends are long-term modifications, not just brief fluctuations.) One such trend is an increase in average size. You have to stoop to get through the doorways of a Tudor cottage in England because its inhabitants were smaller than you are, not because they had a penchant for crouching. Another trend is in life expectancy. People are living longer. Life expectancy in Africa increased over the past 20 years from 46 to 53 years. Over the same period in Europe, where things were already pretty comfortable to begin with, life expectancy increased from 71 to 75 years. The global average was an increase from 58 to 65 years. What do such trends have to do with athletic performance? Well, if we're living longer and growing up faster, that must mean we're producing bigger, better bodies. Better bodies imply faster miles. We run faster and faster for the same reason it is now common for 11-year-old girls to menstruate. But why are these things happening? The decline of empire has its Olympic corollaries. Britain won, on average, 17 gold medals per Olympics in the five official games held in its imperial heyday before World War I. That average has dropped to only five medals per Olympics in the 17 held since. This is not a reflection of declining athletic standards in Britain, however it's a function of how much more competitive other nations have become. The Olympics originally were the preserve of the socioeconomic elite of the socioeconomic elite among nations. Consider this: Only 13 nations participated in 1896, but there were 172 in 1992. Black Africans didn't take part until the third modern games, held in St. Louis in 1908. Even this was accidental: Lentauw and Yamasami, Zulu tribesmen, entered the marathon because they happened to be in St. Louis as part of an exhibit about the Boer war. Lentauw finished ninth despite being chased into a cornfield by dogs. Since all these are changes in how we live, not anything innate, we have to conclude that what we are describing here are effects of environment, not genes. Let us assume that our 1900 and 1990 12-year-olds are identical twins magically born 90 years apart. The 1990 girl still will grow up faster, end up bigger, menstruate earlier, and live longer than the 1900 girl. Perhaps way, way back in human history, when our forebears were still fleeing saber-toothed tigers, natural selection for athletic prowess came into play. But all that ended long ago. Indeed, the laws of natural selection probably work against athletes these days: Given the rigors of training schedules, it is possible that today's top athletes have fewer children than average. Just because nurture has a more significant effect on athletic performance doesn't mean that nature lies dormant, though. Genetic variation exists for just about any trait you choose to study, and the ability to run quickly would be no exception. To take a trivial case, we know that the inheritance of extra fingers or toes is determined genetically. It is quite possible that the possession of an extra toe would hinder an aspiring miler--their genes have affected their athletic performance. One genetic factor that may be influencing performance trends is what is known as "hybrid vigor." Cattle breeders have known about this for a long time: Take two inbred lines of cattle, cross them, and what you have is "better" (say, larger) than any single individual in either of the two parental lines. This does not require natural selection That doesn't mean, however, that genetic differences in athletic ability can be correlated automatically with race. That is a claim that is impossible to test, because you cannot control, in an experimental sense, environmental differences among the study groups. Sure, you will find more Africans or descendants of Africans standing on the podiums at the end of Olympic track events. And you will find far fewer Asians on those same podiums. But can you, therefore, conclude that Africans have better genes for running than Asians do? No. Environmental differences between the two groups could account for differing levels of athletic success. It is scarcely surprising that Ethiopian or Kenyan distance runners do better than everyone else, since they are in the habit of running immense distances to and from primary school, middle school, and high school. The training is what's crucial, not the blackness. The Chinese sports establishment also has carried out an enormous, and effective, experiment to help dispel the myth that race has a direct relation to athletic ability. Until recently, a quick glance at the medals table confirmed every stereotype people held about Asians and sports. Then the Chinese decided to produce record-breaking female distance runners (and swimmers), and, boy, did they ever. In 1992, China ranked fourth in the Olympic-medal haul.

<question>:
What did the Chinese do to help dispell the idea that racial differences determined racing speed?

<options>:
A The Chinese conducted extremely effective selection events. With a billion people, they were well-positioned to find more good runners if they just looked.
B They divided one thousand people into two groups. One group got only the traditional Chinese diet and health care, the other group got every modern advance and a good diet. They got faster runners from the "good care" group.
C China doesn't just consist of one race, and their Olympic team members do well from all the Chinese races such as the Mongolians, Uigars, Tibetans and Mandarins.
D Starting from nothing, they dramatically improved the performance of their women distance event competitors by improving their training, to rank fourth in medals won  in the Olympics of the early 1990s.

<answer>:

D