Which element of the setting also becomes a main character in The Adventures of Huckleberry Finn?

the state of Missouri

the historical time period

the Civil War

the Mississippi River

The correct answer is The Mississippi River

The river is almost as if one of the characters because it is there constantly and it takes the crew from one place to another. It is like a guide that carries them from adventure to adventure and many thus consider it to be like one of the characters.