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 dam is to be constructed across a valley to form a reservoir, and the areas in the following table enclosed by contour loops were obtained from a plan of the area involved.If the 660 m level represents the level floor of the reservoir, use the prismoidal formula to calculate the volume of water impounded when the water level reaches 700 m.<image 1>
A. 29.893 * 106 $m^{3}$
B. 29.293 * 106 $m^{3}$
C. 29.493 * 106 $m^{3}$
D. 29.693 * 106 $m^{3}$

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
D
A dam is to be constructed across a valley to form a reservoir, and the areas in the following table enclosed by contour loops were obtained from a plan of the area involved.If the 660 m level represents the level floor of the reservoir, use the prismoidal formula to calculate the volume of water impounded when the water level reaches 700 m.<image 1>
A. 29.893 * 106 $m^{3}$
B. 29.293 * 106 $m^{3}$
C. 29.493 * 106 $m^{3}$
D. 29.693 * 106 $m^{3}$

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