You are given a science question (hard-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.
--------
Question: Which question will best help a student determine the composition of an unknown substance?  
 (A) Is the sample warm or cold? (B) How valuable is the sample? (C) Has the sample ever been melted? (D) Does the sample conduct electricity?

Answer: D


Question: Farmers in Wyoming were concerned because some of their chickens were being preyed upon by hawks that lived in areas around their ranches. The farmers grouped together and hunted the hawks until they were no longer in their area. Which would most likely happen next?  
 (A) The chicken population would go down. (B) Populations of mice and rats would increase. (C) Another bird of prey would replace the hawk. (D) The chickens would have a lower rate of disease.

Answer: B


Question: Which of the following best describes a learned behavior?  
 (A) owls looking for food at night (B) monarch butterflies migrating south (C) cats pawing the area where they are going to sleep (D) fish swimming to the top of an aquarium to get food

Answer:
D