challenge: Where is Aktove Canyon located?
  
  A. On the Dnieper river in the Kherson Oblast of Ukraine
  B. On the Mertvovod river in the Voznesensk Raion of Mykolaiv Oblast of Ukraine
  C. On the Danube river in the Odessa Oblast of Ukraine
  D. On the Don river in the Zaporizhzhia Oblast of Ukraine
  Answer: 