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>Find the dimensions of the right circular cylinder of maximum volume that can be inscribed in a right circular cone of radius R and height H (Fig. 16-17).<image 1>
A. r = 2R/3
B. r = 3R/2
C. r = R/3
D. r = 2R

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
Find the dimensions of the right circular cylinder of maximum volume that can be inscribed in a right circular cone of radius R and height H (Fig. 16-17).<image 1>
A. r = 2R/3
B. r = 3R/2
C. r = R/3
D. r = 2R

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