question: As shown in the figure, it is known that BA is the tangent of circle O, and connect OB to intersect circle O at point C. If angle B = 45.0 and the length of AB is 2.0, then the length of BC is ()
  Choices:
  A:2√{2}-1
  B:√{2}
  C:2√{2}-2
  D:2-√{2}
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, it is known that BA is the tangent of circle O, and connect OB to intersect circle O at point C. If angle B = 45.0 and the length of AB is 2.0, then the length of BC is ()
  Choices:
  A:2√{2}-1
  B:√{2}
  C:2√{2}-2
  D:2-√{2}
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, it is known that BA is the tangent of circle O, and connect OB to intersect circle O at point C. If angle B = 45.0 and the length of AB is 2.0, then the length of BC is ()
  Choices:
  A:2√{2}-1
  B:√{2}
  C:2√{2}-2
  D:2-√{2}
question_for_eval: As shown in the figure, it is known that BA is the tangent of circle O, and connect OB to intersect circle O at point C. If angle B = 45.0 and the length of AB is 2.0, then the length of BC is ()
  Choices:
  A:2√{2}-1
  B:√{2}
  C:2√{2}-2
  D:2-√{2}