The correct answer to this open question is the following.
Countries have a responsibility to cooperate with each other.
In a global world like the one we are living now, countries need other countries in order to trade, sign treaties of mutual help, and have allies in moments of need.
It is very difficult for a country to live isolated from the world. Othe countries have goods and services that the other does not have. That is why cooperation is the right foreign policy to maintain good relations and to solve difficulties when problems appear.