question: Hint: Please answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: As shown in the figure, points A, B, C, and D are on circle O, and point E is on the extended line of AD. If ∠ABC = 60.0, then the degree of ∠CDE is ()
  Choices:
  (A) 30°
  (B) 45°
  (C) 60°
  (D) 70°