Ronald Reagan was elected president in 1981.
Answer:
c. Osama Bin Laden
Explanation:
He was the one that plotted the entire thing.
poltical and economic isolation
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.