The Old Adage "Politics Stops at the Water's Edge" Means

The old adage "politics stops at the water's edge" means that

A) debates about irrigation policy should be settled by making reference to the Constitution, not by voting in Congress.
B) all Americans will suffer if we fail to work together to protect our nation's political, economic, and security interests in the wider world.
C) the United States should not have policy disagreements with other countries.
D) Democrats and Republicans should only disagree with each other on foreign policy issues and not on matters of domestic policy.