The correct answer is B) : a conductor who guides people on the Underground Railroad.
" Go Down, Moses" is said to be a spiritual as it is associated with the southern African American people,who live in the south of U.S,and the oppression they were living in the Underground Railroad. This type of songs remembers them there may be a possibility to escape to be free.
There is a direct reference with the biblical episode of Moses liberating the Israelites from the Egyptians. In this case, Moses is the abolitionist who wants to conduct the slaves out of the Underground Railroad and take them to freedom.