According to paragraph 4, which of the following statements about steam engines is true？A．

According to paragraph 4, which of the following statements about steam engines is true？

A．They were used for the production of paper but not for printing.

B．By 1800, significant numbers of them were produced outside of Britain.

C．They were used in factories before they were used to power trains.

D．They were used in the construction of canals and turnpikes.

请帮忙给出正确答案和分析，谢谢！