Which of the following factors influenced the growth of the Ruhr Valley?

The main factor that influenced the growth of the Ruhr Valley was industrialization. The Ruhr Valley was rich in coal and iron ore, which were essential resources for the growth of heavy industries like steel and machinery. The availability of these resources, combined with the good transportation network and the presence of a large workforce, made the Ruhr Valley an attractive location for industrial development. This led to a rapid growth of the region's economy and population. Soil fertility, good climate, and agriculture also played a role, but industrialization was the driving force behind the growth of the Ruhr Valley.