单选题 1分

Large numbers of state-run preschools were expediently closed down during the 1990s economic reform ...

Large numbers of state-run preschools were expediently closed down during the 1990s economic reform and instead,a variety of for-profit private preschools sprung ______ across the country.
  • A.by
  • B.out
  • C.in
  • D.up