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><image 1> Why are the branches of the old ash tree located next to the main road withering?
A. Don't know or not sure
B. Repeated root damage by tractors in adjacent field (abiotic)
C. Fungal dieback ('ash dieback')
D. Air pollution damage
E. Combination of fungal and abiotic dieback

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
<image 1> Why are the branches of the old ash tree located next to the main road withering?
A. Don't know or not sure
B. Repeated root damage by tractors in adjacent field (abiotic)
C. Fungal dieback ('ash dieback')
D. Air pollution damage
E. Combination of fungal and abiotic dieback

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