阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项，并在答题卡上将该项涂黑。
A
Historians say Harriet Tubman was born in the year 1820.Nobody really knows.But we do know that Harriet Tubman was one of the bravest women ever born in the United States.
From a very early age, Harriet knew how slaves suffered. At six years old, she was sent to the fields.Working outside not only made her body strong but also made her learn about the Underground Railroad, on which she helped hundreds of people escape from slavery later.She also learned many things
