The railroad industry.
Explanation:
George Westinghouse was an American innovator that had huge impact on the development of the railroad industry. His most notable innovation that improved the railroad industry was the railway air break. This was extremely important, especially in the 19th century, as the trains often found themselves in a situation where a highly efficient break is needed urgently, but they didn't had such at disposal.
Many accidents have happened because of the inefficient breaks, so when Westinghouse came up with his railway air break it was seen as a savior invention which will help the railroad industry a lot when it comes to accidents, repairs, or constantly making new trains. Westinghouse put in all of his effort and finances into patenting and promoting this innovation, as well as the others he had, and it paid off for him over time.
The answer is option D "a document made by someone who actually saw an event." A primary source would be like a witness during a event. They can give reliable information on what happened during that event. Main primary sources are: documents, pictures or photographs, and objects that can explain what happened during a event.
Hope this helps!
1) A
that's the only one I know sorry
D. It was a period of intellectual and artistic creativity.
