He came to power because he was a great orator and convinced the people that they were doing the right thing. He promised change and replaced the weak government they had before.
The answer that you're seeking is, "Trains from different rail lines could use each other’s tracks." The standardization of rails allowed trains to use eachothers tracks and increase speed and efficieny in deliveries. Hope I helped!
The right choice to your question is A. a chemist who created vaccines against Cholera, rabies and anthrax. ~~~ Check the meaning of Pasteurization.
A is the answer to this question :) sorry if it’s wrong