A、George Washington. B、A black slave. C、A slave owner. D、A Quaker. D原文提到，人们认为the Underground Railroad是由一个名字叫Isaac Hopper——基督教贵格会

Good afternoon! Today I would like to talk about the Underground Railroad. Now, one of the most interesting events, I think, in Afro-American history, was the development of the Underground Railroad in the years before the Civil War. I guess you’ve all heard of that, right? Then you know that the Underground Railroad wasn’t a real railroad—it just got that name, in about 1831, because at that time the new steam engines, the new steam railways, were becoming important in the US economy.
    So, the Underground Railroad wasn’t a railroad—it was a network of people who helped slaves in the South escape to the North, to the northern states and to Canada, mostly, but also to the West, to Mexico, and to the Caribbean as well. These people were black and white, abolitionists and free Blacks and various religious groups, and they helped slaves escape from their masters. They hid them in their houses, and they secretly conveyed them by wagon, by boat, and on foot—to places where human slavery was illegal.
    It’s believed that the system was started by a Quaker, Isaac Hopper, near the end of the 18th century, because he had begun organizing ways to assist runaway slaves at that time. It’s documented that, in 1786, George Washington—before he became the first US President—complained that one of his slaves was helped to escape by, quote, "a society of Quakers, formed for such purposes", unquote.
    The Underground Railroad never was extensively organized, though It was just an informal network of safe houses and secret routes and meeting points. The people involved didn’t know any of the details of operations beyond those in their own immediate area—probably just enough to convey fugitives to the next station
    The participants used a kind of code, a kind of jargon, based on railway terms. The various hiding locations were called "stations", so the people who hid the runaways were called "stationmasters", and the people who guided them along the route, who transported them from meeting place to meeting place, were called "conductors". And the escaped slaves themselves were referred to as "passengers". One station-master, William Steel, helped hundreds of escaping slaves-as many as sixty a month,and he kept careful records, including individual biographies, that included these railway code phrases. Then he later published these accounts, after the war, in 1872.
23. What does the speaker say about the Underground Railroad?
24. Who is believed to have started the Underground Railroad?
25. What did people call the runaway slaves?