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> Examine the detached branches of Gliricidia sepium, a common species used in tropical agroforestry. How does the sickly, yellowed leaves on the left contrast with the normal growth adjacent to it, given that both are part of the same tree? The symptoms are not evenly spread across the crown of the tree. Have you noticed that some of the branches have begun to die?
A. Virus infection
B. Herbicide damage
C. Fungus disease
D. Phytoplasma
E. Don't know, not sure

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
D
<image 1> Examine the detached branches of Gliricidia sepium, a common species used in tropical agroforestry. How does the sickly, yellowed leaves on the left contrast with the normal growth adjacent to it, given that both are part of the same tree? The symptoms are not evenly spread across the crown of the tree. Have you noticed that some of the branches have begun to die?
A. Virus infection
B. Herbicide damage
C. Fungus disease
D. Phytoplasma
E. Don't know, not sure

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