Read the line from Hamlet cited in Shakespeare: The World as Stage.

Barnardo: Who's there?

What does this line most likely show about the setting of the scene?

It takes place in a foreign land because Barnardo does not know everyone.
It is dark because Barnardo has trouble seeing the other guard.
It takes place in a castle because Barnardo is a guard.
It is early in the morning because Barnardo arrives first on the scene.

The line "Who's there?" spoken by Barnardo most likely shows that the scene takes place in a castle because Barnardo is a guard.