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 internal angles of a pentagon are shown in the diagram. The coordinate bearing angle of side $L_{12}$ is $\alpha_{12}=30°$. Calculate the coordinate bearing angles of the other sides.<image 1>
A. $\alpha_{23}=75°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
B. $\alpha_{23}=95°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
C. $\alpha_{23}=65°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
D. $\alpha_{23}=85°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$

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 internal angles of a pentagon are shown in the diagram. The coordinate bearing angle of side $L_{12}$ is $\alpha_{12}=30°$. Calculate the coordinate bearing angles of the other sides.<image 1>
A. $\alpha_{23}=75°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
B. $\alpha_{23}=95°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
C. $\alpha_{23}=65°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$
D. $\alpha_{23}=85°$,$\alpha_{34}=160°$,$\alpha_{45}=220°$,$\alpha_{51}=280°$

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