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 railway embankment 400 m long is 12 m wide at the formation level. The side slope of the embankment is 2:1. The formation level at zero chainage is 107.00. The embankment has a rising gradient of 1 in 100. The ground is level across the c/l. Calculate the volume of earthwork using the prismoidal rule with the following observations:<image 1>
A. 14563 $m^{3}$
B. 14583 $m^{3}$
C. 14553 $m^{3}$
D. 14573 $m^{3}$

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
A railway embankment 400 m long is 12 m wide at the formation level. The side slope of the embankment is 2:1. The formation level at zero chainage is 107.00. The embankment has a rising gradient of 1 in 100. The ground is level across the c/l. Calculate the volume of earthwork using the prismoidal rule with the following observations:<image 1>
A. 14563 $m^{3}$
B. 14583 $m^{3}$
C. 14553 $m^{3}$
D. 14573 $m^{3}$

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