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 following cyclisation <image 1> is part of a synthesis of quinagolide. Which of the following statements is true?
A. The cyclisation is defined as 6-exo-tet and is allowed by Baldwin's rules
B. The cyclisation is defined as 6-exo-trig and is allowed by Baldwin's rules
C. The cyclisation is defined as 6-endo-tet and is allowed by Baldwin's rules
D. The cyclisation is defined as 6-endo-trig and is allowed by Baldwin's rules

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
C
The following cyclisation <image 1> is part of a synthesis of quinagolide. Which of the following statements is true?
A. The cyclisation is defined as 6-exo-tet and is allowed by Baldwin's rules
B. The cyclisation is defined as 6-exo-trig and is allowed by Baldwin's rules
C. The cyclisation is defined as 6-endo-tet and is allowed by Baldwin's rules
D. The cyclisation is defined as 6-endo-trig and is allowed by Baldwin's rules

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