通读下面的短文，掌握其大意。然后，从每小题的四个选择项中选出可填入相应空白处的最佳选项。

     Yuichiro Miura lives by the saying that nothing is impossible. For him, that means climbing Qomolangma, the world's highest mountain, at the age of 80. He  to climb it for the  time next month. He reached its top at ages 70 and 75. If he succeeds this time, he will  the record for the oldest person to climb the 8, 844-meter-high mountain.
     The record, , is not what pushes him on. Instead, he wants to know how a person of his age will  and deal with the terrible cold,  air and low oxygen (氧气) levels on such a high mountain. He believes those  will add 70 years to the age of his body once he  to the top. His daughter, Emili Miura,  others that he will feel like someone 150 years old.
     "Nobody ever lived that long, and he's so  to know how it would be like," she said. "He would like to know what is the  of humans." Emili Miura said her father thinks that one should always set a higher  for oneself and try to achieve it.
     Yuichiro Miura faces more dangers  health problems. He has had three heart operations in  years, and he suffered two  bones in a sport accident in 2009. Nobody would say it's wise for an 80-year-old person to make the climb, but Mr. Miura believes that nothing is impossible.