Which of the Following Statements About Harriet Tubman Is MOST

Which of the following statements about Harriet Tubman is MOST accurate?

A) She is generally credited with having established the Underground Railroad.
B) She was the only black conductor willing not only to assist runaway slaves,but to risk forays into the South to free them.
C) She developed a system for escapes based on daylight hours and newspaper publication dates.
D) Despite her exploits,she remained unknown until she revealed the details of her former career after the Civil War.