challenge: Where does Wyoming Highway 321 (WYO 321) begin?
  
  A. At the junction with WYO 313 in Chugwater
  B. At a diamond interchange with concurrent highways I-25 and US 87 on the north side of Chugwater
  C. At a diamond interchange with concurrent highways I-25 and US 87 on the south side of Chugwater
  D. At exit 57 of I-25
  Answer: 