The factor that made American industrial growth possible was:
- An increase in importing materials.
Explanation:
1. American industrial growth was facilitated by the ability to import materials from other countries.
2. Importing materials provided the necessary resources for industries to expand and produce goods more efficiently.
3. This access to imported materials helped fuel the growth of industries such as manufacturing, steel production, and more.
4. It allowed American businesses to access a wider variety of resources that could not be sourced domestically, contributing to economic development and industrial expansion.
Therefore, the correct answer to the question is "An increase in importing materials."
