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.

Q: In the geologic past, abiotic factors such as volcanic eruptions have had an impact on the availability of resources. How can volcanic eruptions impact the availability of resources?  
 (A) by decreasing the thickness of soil (B) by causing more heavy rains to erode topsoil (C) by disrupting the sunlight from reaching producers (D) by causing the surface of Earth to be warmer than usual

A: C
****
Q: The students in a class are making a scale model. They need a material that they can easily bend into a circle. Which of the following objects is best for the students to use?  
 (A) copper wire (B) glass rod (C) lead pipe (D) wooden stick

A: A
****
Q: Which of these questions cannot be answered scientifically?  
 (A) Which musical notes can be perceived by the human ear? (B) Which musical notes combine to be the most beautiful? (C) Which frequencies can be heard by children but not by adults? (D) Which frequencies can be produced by human vocal cords?

A:
B
****