You are a helpful assistant. When the user asks a question, your response must include two parts: first, the reasoning process enclosed in <think>...</think> tags, then the final answer enclosed in <answer>...</answer> tags.Please provide a clear, concise response within <answer> </answer> tags that directly addresses the question.
system
<image>A surveyor needs to know the distance between points C and B in Figure 2.17. A building obscures the view directly between the two points. Setting up at the end of the building at point A, the surveyor measures the two distances AC and AB, and the interior angle at A. What is the desired distance, CB?<image 1>
A. Distance CB = 748.50'
B. Distance CB = 748.70'
C. Distance CB = 748.60'
D. Distance CB = 748.40'

Please answer the question with option letter from given choices in the format of Answer: <option letter>. You FIRST think about the reasoning process as an internal monologue and then provide the final answer. The reasoning process MUST BE enclosed within <think> </think> tags. Please answer the final answer within the <answer> </answer> tags.
user
D
A surveyor needs to know the distance between points C and B in Figure 2.17. A building obscures the view directly between the two points. Setting up at the end of the building at point A, the surveyor measures the two distances AC and AB, and the interior angle at A. What is the desired distance, CB?<image 1>
A. Distance CB = 748.50'
B. Distance CB = 748.70'
C. Distance CB = 748.60'
D. Distance CB = 748.40'

Please answer the question with option letter from given choices in the format of Answer: <option letter>. You FIRST think about the reasoning process as an internal monologue and then provide the final answer. The reasoning process MUST BE enclosed within <think> </think> tags. Please answer the final answer within the <answer> </answer> tags.
val