Question

the main purpose of the g20 is to
provide rules for international trade.
offer help to developing countries.
cooperate to prevent financial crises.
give loans to struggling economies.

Explanation:

The G20 is an international forum of the world's major economies. Its main purpose is to promote international financial stability and cooperation to prevent financial crises. It is not mainly about providing international - trade rules (that's more of the WTO's role), offering help specifically to developing countries as its main focus, or giving loans (which is more the role of the IMF and World Bank).

Answer:

cooperate to prevent financial crises.