You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Q: To calculate the relative age of rocks, geologists use the rate of radioactive decay of isotopes present in their samples. What is the term used for the original amount of the elemental isotopes being investigated?   
 (A) rare earth isotopes (B) son isotopes (C) daughter isotopes (D) parent isotopes

A: D
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Q: How does sedimentary rock form?  
 (A) sediments cool (B) sediments melt (C) sediments separate (D) sediments compress

A: D
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Q: A class learns about weather. The students in the class measure the outside air temperature at the same time each day. Which way of measuring the temperature would provide the most accurate data?  
 (A) taking the measurement in the shade (B) placing the thermometer on the ground (C) taking a measurement using a different tool each day (D) recording the measurements from three thermometers

A:
D
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