The containment policy and the NATO(North Atlantic Treaty Organization).
D. Provide health care and welfare
The example that best illustrates checks and balances is A) The Supreme Court rules that a law passed by Congress is unconstitutional.
The principle of checks and balances ensures that one branch of the government does not have an excess of power over any of the others.
In this example, Congress passed a law - however the Supreme Court ruled that it was unconstitutional, and therefore they struck it down.
This principle helps to balance out the government so that one branch does not have any more say than the others.