In this task, you are given a text which is the body of a document. You are given a question and options. Pick the correct number. Don't generate anything else apart from the numbers provided in options.
Q: Context: The Elvo (Piedmontese: Elv) is a 53 km torrent (an intermittent stream) in the Piedmont region of north-west Italy and is the principal tributary of the Cervo. It runs through the communes of Sordevolo Occhieppo Superiore Occhieppo Inferiore Cerrione and Salussola in the Province of Biella and of Carisio and Casanova Elvo in the Province of Vercelli. The river's valley is named after it as the Valle dell'Elvo.
Question: The document can be classified to which topic?
Options: 1)Athlete, 2)Animal, 3)MeanOfTransportation, 4)Album, 5)NaturalPlace
A:
5