The correct answer is - demand.
Trade is a result of the uneven distribution of resources and demand of the same. We have lots of examples throughout the world, some where we have less developed economies that have lots of resources, and vice versa, highly developed economies that lack their own resources. We can take Kosovo and Japan for example, as two countries on the total opposite ends of the economic spectrum. Kosovo is a country that has very big amounts of quality coal at disposal, but it is not a developed country, and the amount of coal needed for its own economy is very small, but since there's still big demand for it, they are exporting the coal to the countries that need it but don't have it. Japan, on the other hand, is one of the most developed countries in the world, but when it comes to natural resources it is a very poor country, so they are dependent on import of resources in order to be able to sustain their economy and progress.
