Answer:
Land, labor, capital and technology.
Explanation:
Land, labor, capital and technology are the four factors that is responsible for the industrial development in the Ruhr region. If the land is full of mineral resources, then the international and national companies comes to invest in that region for the extraction of minerals. Labor is also needed in order to extract minerals from the land as well as technology is required for the easiness in the extraction of minerals from the land.
