Stable political conditions and freedom (from) foreign invasion enable a country to develop its natural resources peacefully and steadily, and (to produce) more wealth than (the other) country equally well served by nature but (less well) ordered.

A．it results in war in most cases
B．it induces efforts to expand territory
C．it is a kind of opposition among social entities
D．it is essentially a struggle for existence

A．space travel
B．life on other planets
C．ecological problems on earth
D．wars between the earth and other planets