In the following paragraph, what pronouns should be used in the blanks so that the paragraph can be more coherent?
"Olympic athletes must be strong both physically and mentally. First of all, if an athlete hopes to compete in an Olympic sport, _____ must be physically strong. Furthermore, aspiring Olympians must train rigorously for many years. For the most demanding sports, they train several hours a day, five or six days a week, for ten or more years. In addition to being physically strong, athletes must also be mentally tough. This means that _____ have to be totally dedicated to _____ sports, often giving up a normal school, family, and social life. Being mentally strong also means that he must be able to withstand the intense pressure of international competition with its accompanying media coverage. Finally, not everyone can win a medal, so _____ must possess the inner strength to live with defeat."
A、you; he; his; you
B、he; they; their; an Olympian
C、they; you; your; they
D、he or she; one; his; someone