单项选择题

Questions 8 to 10 are based on the following news. At the end of the news item, you will be given 10 seconds to answer each question. Now listen to the news. What is the problem with Russia’s space station

A.It has lost its primary 6xygen sources.
B.It has lost its backup oxygen sources.
C.It has lost both the primary and the backup oxygen sources.
D.It has last neither the primary or the backup oxygen sources.