question: As shown in the figure, AB is the diameter of circle O, point C is on circle O, passing point C to draw the tangent of circle O and it intersects the extended line of AB at point D. Connect AC. If angle D = 50.0, then the degree of angle A is ()
  Choices:
  A:20°
  B:25°
  C:.40°
  D:50°
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, AB is the diameter of circle O, point C is on circle O, passing point C to draw the tangent of circle O and it intersects the extended line of AB at point D. Connect AC. If angle D = 50.0, then the degree of angle A is ()
  Choices:
  A:20°
  B:25°
  C:.40°
  D:50°
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, AB is the diameter of circle O, point C is on circle O, passing point C to draw the tangent of circle O and it intersects the extended line of AB at point D. Connect AC. If angle D = 50.0, then the degree of angle A is ()
  Choices:
  A:20°
  B:25°
  C:.40°
  D:50°
question_for_eval: As shown in the figure, AB is the diameter of circle O, point C is on circle O, passing point C to draw the tangent of circle O and it intersects the extended line of AB at point D. Connect AC. If angle D = 50.0, then the degree of angle A is ()
  Choices:
  A:20°
  B:25°
  C:.40°
  D:50°