Which of the following best explains why the Rhine-Ruhr area became a major industrial area?

• It has flat land and rich soil.
• It has major iron and coal deposits
• It has a large population.
• It is centrally located in Europe.

The best explanation for why the Rhine-Ruhr area became a major industrial area is that it has major iron and coal deposits. These natural resources played a crucial role in the development and growth of industry in the region. Iron and coal are essential raw materials for industrial production, and the presence of abundant deposits allowed for the establishment of steel mills, factories, and other industrial facilities.