Question: Oka (Russian: IPA: [ka]) is a river in central Russia the largest right tributary of the Volga. It flows through the regions of Oryol Tula Kaluga Moscow Ryazan Vladimir and Nizhny Novgorod and is navigable over a large part of its total length as far upstream as to the town of Kaluga. Its length exceeds 1500 kilometres (930 mi). The Russian capital Moscow sits on one of the Oka's tributariesthe Moskva River. Given a list of categories: company, educational institution, artist, athlete, office holder, mean of transportation, building, natural place, village, animal, plant, album, film or written work, what category does the paragraph belong to?
Answer:
Natural Place