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>An 82-year-old woman presents to the office with a 1-year history of worsening cough and shortness of breath. She has a 45 pack-year history of cigarette smoking and quit smoking 15 years ago. Vital signs reveal: <image 1>. ECG findings are normal. Her FEV1/FVC ratio is 65% of predicted. The most appropriate inhaled medication for this patient works by blocking which of the following receptors?
A. $\beta $1-adrenergic receptors
B. glucocorticoid receptors
C. histamine H1 receptors
D. leukotriene receptors
E. muscarinic receptors

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
E
An 82-year-old woman presents to the office with a 1-year history of worsening cough and shortness of breath. She has a 45 pack-year history of cigarette smoking and quit smoking 15 years ago. Vital signs reveal: <image 1>. ECG findings are normal. Her FEV1/FVC ratio is 65% of predicted. The most appropriate inhaled medication for this patient works by blocking which of the following receptors?
A. $\beta $1-adrenergic receptors
B. glucocorticoid receptors
C. histamine H1 receptors
D. leukotriene receptors
E. muscarinic receptors

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