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>The results of a prospective cohort study of smoking and lung cancer were as follows.<image 1> The attributable risk(AR) was
A. 11.6
B. 53.0/100000
C. 63.0/100000
D. 0.91

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
B
The results of a prospective cohort study of smoking and lung cancer were as follows.<image 1> The attributable risk(AR) was
A. 11.6
B. 53.0/100000
C. 63.0/100000
D. 0.91

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