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>Suppose that a typical market based in Japan consists of 200 Apples and 290 Textbooks. The table below shows data on prices for Apples and Textbooks in Japan for three years. <image 1> Assume that the base year is 2015. What is CPI in 2015?
A. 100
B. 200
C. 300
D. 400

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
A
Suppose that a typical market based in Japan consists of 200 Apples and 290 Textbooks. The table below shows data on prices for Apples and Textbooks in Japan for three years. <image 1> Assume that the base year is 2015. What is CPI in 2015?
A. 100
B. 200
C. 300
D. 400

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