Which of the following best describes how the european union works?
a. member nations manipulate oil prices by increasing and
decreasing production.
b. member nations buy and sell all of the world's products,
dc. member nations agree to use the same form of government.
d. member nations combine and coordinate their economies.

D. Member nations combine and coordinate their economies.

Explanation:

The European Union is a single common market with the same rules, where competitors from other EU countries compete under the same conditions with a local member´s firms. The EU, and that´s the work of its executive branch the European Commission, has uniform norms and standards; all its members must follow similar macroeconomic, fiscal and trade policies.