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 61-year-old woman comes to her physician because of a change in the appearance of her right breast over the past 7 months. On physical examination the skin overlying the breast is indurated, roughened, and reddish-orange. There is nipple retraction. The gross appearance of the cut surface of her subsequent mastectomy specimen is shown here. Which of the following is the most likely diagnosis? <image 1> 
A. Infiltrating ductal carcinoma
B. Intraductal carcinoma
C. Phyllodes tumor
D. Lobular carcinoma in situ

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 61-year-old woman comes to her physician because of a change in the appearance of her right breast over the past 7 months. On physical examination the skin overlying the breast is indurated, roughened, and reddish-orange. There is nipple retraction. The gross appearance of the cut surface of her subsequent mastectomy specimen is shown here. Which of the following is the most likely diagnosis? <image 1> 
A. Infiltrating ductal carcinoma
B. Intraductal carcinoma
C. Phyllodes tumor
D. Lobular carcinoma in situ

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