challenge: What is the highest point in Dunn County, North Dakota?
  
  A. A valley in the southwestern part of the county, at 2,000 ft (610 m) ASL
  B. A hill at the southwestern corner, at 2,625 ft (800 m) ASL
  C. A hill at the northeastern corner, at 2,625 ft (800 m) ASL
  D. A plateau in the central part of the county, at 2,500 ft (760 m) ASL
  Answer: 