question: The figure shows a quadrilateral ABCD, with S on AC and T on BD. For trapezoid A B C D, S and T are midpoints of the legs. If A B = x + 4, C D = 3 x + 2, and S T = 9, find A B.
  Choices:
  A:3
  B:5
  C:7
  D:9
query_wo: Please directly answer the question and provide the correct option letter, e.g., A, B, C, D.
  Question: The figure shows a quadrilateral ABCD, with S on AC and T on BD. For trapezoid A B C D, S and T are midpoints of the legs. If A B = x + 4, C D = 3 x + 2, and S T = 9, find A B.
  Choices:
  A:3
  B:5
  C:7
  D:9
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: The figure shows a quadrilateral ABCD, with S on AC and T on BD. For trapezoid A B C D, S and T are midpoints of the legs. If A B = x + 4, C D = 3 x + 2, and S T = 9, find A B.
  Choices:
  A:3
  B:5
  C:7
  D:9
question_for_eval: The figure shows a quadrilateral ABCD, with S on AC and T on BD. For trapezoid A B C D, S and T are midpoints of the legs. If A B = x + 4, C D = 3 x + 2, and S T = 9, find A B.
  Choices:
  A:3
  B:5
  C:7
  D:9