question: Hint: Please answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: 如图，一块直角三角板60°的角的顶点A与直角顶点C分别在两平行线FG，DE上，斜边AB平分∠CAG，交直线DE于点H，则∠BCH的大小为（）
  Choices:
  (A) 60°
  (B) 45°
  (C) 30°
  (D) 25°