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>An experiment is performed to measure the mass percent of $CaCO_3$(s) in eggshells. Five different samples of $CaCO_3$(s) of known mass react with an excess of 2.0 M $HCl$(aq) in identical sealed, rigid reaction vessels. The pressure of the gas produced is measured with a pressure gauge attached to the reaction vessel. Since the reaction is exothermic, the reaction system is cooled to its original temperature before the pressure is recorded. The experimental data are used to create the calibration line below. <image 1> The experiment is repeated with an eggshell sample, and the experimental data are recorded in the table below. <image 2> Which of the following modifications will increase the rate of the reaction the most? 
A. Using 2.0 M $CH_3COOH$(aq) instead of 2.0 M $HCl$(aq) 
B. Cooling the $HCl$(aq) to a lower temperature than it was in the original experiment
C. Reducing the volume of the reaction vessel
D. Using eggshells that are more finely powdered than those used in the original experiment 

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
An experiment is performed to measure the mass percent of $CaCO_3$(s) in eggshells. Five different samples of $CaCO_3$(s) of known mass react with an excess of 2.0 M $HCl$(aq) in identical sealed, rigid reaction vessels. The pressure of the gas produced is measured with a pressure gauge attached to the reaction vessel. Since the reaction is exothermic, the reaction system is cooled to its original temperature before the pressure is recorded. The experimental data are used to create the calibration line below. <image 1> The experiment is repeated with an eggshell sample, and the experimental data are recorded in the table below. <image 2> Which of the following modifications will increase the rate of the reaction the most? 
A. Using 2.0 M $CH_3COOH$(aq) instead of 2.0 M $HCl$(aq) 
B. Cooling the $HCl$(aq) to a lower temperature than it was in the original experiment
C. Reducing the volume of the reaction vessel
D. Using eggshells that are more finely powdered than those used in the original experiment 

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