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>The jet engine in Fig. P3.50 admits air at 20°C and 1 atm at (1), where A_1 = 0.5 m^2 and V_1 = 250 m/s. The fuel-air ratio is 1:30. The air leaves section (2) at 1 atm, V_2 = 900 m/s, and A_2 = 0.4 m^2. Compute the test stand support reaction R_x needed. <image 1>
A. 99,000 N
B. 102,000 N
C. 121,000 N

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
B
The jet engine in Fig. P3.50 admits air at 20°C and 1 atm at (1), where A_1 = 0.5 m^2 and V_1 = 250 m/s. The fuel-air ratio is 1:30. The air leaves section (2) at 1 atm, V_2 = 900 m/s, and A_2 = 0.4 m^2. Compute the test stand support reaction R_x needed. <image 1>
A. 99,000 N
B. 102,000 N
C. 121,000 N

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