What powered the first reliable streetcars?

 The correct answer is : They were driven by electricity

Explanation:  Conventional electric streetcars replaced racing car lines in the United States and Europe. In the United States, horse-drawn cars were replaced by electric trolleys. Both cars and engines were improving little by little.

        i'm fairly sure that the correct answers are 2 and 3.

        i used both my knowledge of world history and the process of elimination to obtain these answers. option 1 cannot be a possible selection because the mandate of heaven belongs to ancient chinese philosophical belief. option 4 sounds like it would benefit the region than detriment it. however, both 2 and 3 explain a potential reason for what could have contributed to the fall of the roman empire.

      hope this ! if i were you, i'd get a second opinion, because i haven't taken this course for a year. best of luck!

***websites that me understand the curriculum better last year are and ***

to protest slavery i would think it would be a