Answer:
A
Explanation:
National Security Act of 1947.
The answer to the question is b
The production of steel was entirely crucial to the development of railroads, since the rail lines themselves were made of steel, without which the trains would not be able to move.
<span>"C. Private firms cut canals at key points and connected
rivers" and "D. Thanks to a web of waterways, boats could reach towns they
had never been able to reach before" are both correct, although roads were beginning to be used more as well. </span>
