question: Hint: Please answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: 如图，点D在等边△ABC的边CB的延长线上，点E在线段BC上，连接AD，AE，若DA＝DE，且∠DAB＝20°，那么∠EAC的度数为（）
  Choices:
  (A) 20°
  (B) 15°
  (C) 10°
  (D) 5°