According to the passage ,the British granted the new American nation a western boundary acted

A．To explain how one state strengthened its land claims.
B．To criticize an effort to acquire additional agricultural resources.
C．To show that many explorers searched for new lands.
D．To question the validity of Virginia's claims.

A．It is the production by termites that is now of greater concern.
B．What scientists worry more about is the output from burning fuels.
C．The output from burning fuels is now rising steadily.
D．The burning of fuels generates much less carbon dioxide than termites do.