According to economist Gary Burtless, What factor accounts for the surge of homeless apart from the economic explanation

A．nuclear war will definitely not take place
B．international agreements are now reached more and more easily
C．man is beginning to realize that nuclear war is his greatest enemy
D．world opinion is in favor of nuclear war

A．will help abolish war
B．put mankind in grave danger
C．will gradually become part of man's life
D．need further improving