The correct answer is option D. "Companies replaced hand-operated brakes with air brakes on trains". The development of air brakes on trains was a significant improvement of railroad safety. Air brakes function much more faster than hand-operated brakes, because hand-operated brakes required that the brakemen turned the brakes in one car and jump to the next to set the brakes on, and so on.
The answer is 10 amendments
Army writing standards consist of simple, easy to read writing, with as little grammatical and spelling errors as possible.
Basically, a simple, clear, summary of whatever you're trying to explain.
Answer:
Ok thank you.
Explanation:
May you please post a link or something so I can do it for you because I do not understand fully.
Thank you!