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> The table shows when each member nation joined the European Union (EU), which was created to reduce trade barriers among member nations. The 1993 Maastricht Treaty founded the EU from its predecessor organization, the European Communities. Which of the following best explains why countries of Eastern Europe were admitted later than other European Union members?
A. Support of these countries' agrarian populations for protectionist trade policies
B. Control of those countries by the Soviet Union until the end of the Cold War
C. Resistance to the West by fascist governments in those countries
D. The greater effect on those countries of the Great Depression and world wars

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
<image 1> The table shows when each member nation joined the European Union (EU), which was created to reduce trade barriers among member nations. The 1993 Maastricht Treaty founded the EU from its predecessor organization, the European Communities. Which of the following best explains why countries of Eastern Europe were admitted later than other European Union members?
A. Support of these countries' agrarian populations for protectionist trade policies
B. Control of those countries by the Soviet Union until the end of the Cold War
C. Resistance to the West by fascist governments in those countries
D. The greater effect on those countries of the Great Depression and world wars

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