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]: In a lab investigation, a student notes that two metal blocks have the same mass. Based on this observation, if the two blocks were put on opposite sides of a balance, they would best represent  
 (A) balanced forces. (B) unbalanced forces. (C) equal and opposite reactions. (D) objects in motion.
[A]: A


[Q]: The ounce, the pound, and the ton are units of  
 (A) time. (B) weight. (C) length. (D) distance.
[A]: B


[Q]: In the Adirondack forests of New York, some trees have died. The change in the forest is thought to be related to air pollution and rain. Which abiotic factor most likely has been changed as a result of the pollution and rain which resulted in the death of the trees?  
 (A) a decrease in the amount of available oxygen (B) an increase in the amount of sunlight (C) a decrease in the pH of the soil (D) an increase in the nutrients
[A]:
C