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 graph <image 1> and a spanning tree <image 2> of <image 1> are given, Give the Fundamental Cut sets of <image 1> with respect of <image 2>
A. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_3$, $e_7$}, {$e_5$, $e_7$, $e_8$}, {$e_6$, $e_8$}
B. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_6$, $e_8$}
C. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_3$, $e_7$}, {$e_5$, $e_7$, $e_8$}, {$e_6$, $e_8$}, {$e_2$, $e_4$}
D. {$e_2$, $e_4$, $e_8$}

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
A graph <image 1> and a spanning tree <image 2> of <image 1> are given, Give the Fundamental Cut sets of <image 1> with respect of <image 2>
A. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_3$, $e_7$}, {$e_5$, $e_7$, $e_8$}, {$e_6$, $e_8$}
B. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_6$, $e_8$}
C. {$e_1$, $e_8$}, {$e_2$, $e_4$, $e_8$}, {$e_3$, $e_7$}, {$e_5$, $e_7$, $e_8$}, {$e_6$, $e_8$}, {$e_2$, $e_4$}
D. {$e_2$, $e_4$, $e_8$}

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