Most of the retired people are happy ______ their quiet life in the countryside.

A．teenagers under 14 are not allowed to visit the White House
B．foreigners are less likely to be permitted to tour the White House
C．separate tours can also be scheduld for individual visitors
D．security is the chief concern in scheduling White House tours

A．it is still possible that your tour may be cancelled
B．you are still allowed to change your visiting date
C．you can surely visit the White House that day
D．it is necessary for you to start your tour immediately