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>For the picture galleries the plans of which are given in Fig. 1, find the smallest number of attendants who, if placed in the various doorways connect two adjacent rooms, can supervise all rooms. Use integer programming and the simplex method to solve.
<image 1>
A. 1 attendant
B. 2 attendants
C. 3 attendants
D. 4 attendants

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
For the picture galleries the plans of which are given in Fig. 1, find the smallest number of attendants who, if placed in the various doorways connect two adjacent rooms, can supervise all rooms. Use integer programming and the simplex method to solve.
<image 1>
A. 1 attendant
B. 2 attendants
C. 3 attendants
D. 4 attendants

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