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]: Students shake salt into a jar of water, and they shake pepper into a second jar of water. Which statement best compares the two jars?  
 (A) Only the salt and water is a mixture. (B) Only the pepper and water is a solution. (C) Both jars contain solutions. (D) Both jars contain mixtures.
[A]: D


[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]: Decomposers are important to the flow of energy in an ecosystem because they  
 (A) are at the top of every food chain. (B) eat things other organisms do not eat. (C) make up a large portion of the top layer of the soil. (D) break organic material into parts that can be reused.
[A]:
D