question: As shown in the figure, chord AC parallel radius OB, then the degree of angle OAB is ()
  Choices:
  A:25°
  B:50°
  C:60°
  D:30°
query_wo: Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
  Question: As shown in the figure, chord AC parallel radius OB, then the degree of angle OAB is ()
  Choices:
  A:25°
  B:50°
  C:60°
  D:30°
query_cot: Please first conduct reasoning, and then answer the question and provide the correct option letter, e.g., A, B, C, D, at the end.
  Question: As shown in the figure, chord AC parallel radius OB, then the degree of angle OAB is ()
  Choices:
  A:25°
  B:50°
  C:60°
  D:30°
question_for_eval: As shown in the figure, chord AC parallel radius OB, then the degree of angle OAB is ()
  Choices:
  A:25°
  B:50°
  C:60°
  D:30°