Final answer:
The Highwayman in the poem is inferred to be a thief who operates on the highway, based on the narrative and English folklore. The correct answer is option B.
Step-by-step explanation:
The best-supported inference about the Highwayman from the entire poem is that he is a thief who steals from people on the highway. This character is central to the narrative and is depicted as a romantic figure, embroiled in a tragic love story with Bess, the innkeeper's daughter. The poem portrays him as a dashing and daring individual, but clearly indicates his role as a robber through lines that describe his interactions with the highway and his ultimate fate at the hands of the Redcoats, who are government forces. This traditional figure of English folklore often engaged in highway robbery, which is consistent with the portrayal in the poem.