challenge: How are aryl selenocyanates typically prepared?
  
  A. Treatment of potassium selenocyanate with alkyl halides in acetone solution
  B. Heating potassium selenocyanate with aryl compounds in a vacuum
  C. Reaction of selenium with aryl halides in water
  D. Treatment of potassium selenocyanate with aryl diazonium salts
  Answer: 