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]: The force of an object, with a certain mass accelerating at a certain rate, can be determined by using the equation below. force = mass x acceleration Which object would have the greatest force?  
 (A) a 5-kg object accelerating at 10 m/s^2 (B) a 5-kg object accelerating at 20 m/s^2 (C) a 20-kg object accelerating at 4 m/s^2 (D) a 20-kg object accelerating at 3 m/s^2
[A]: B


[Q]: Sound is able to travel faster in solids than in air because the molecules in a solid are  
 (A) closer together than air molecules. (B) more easily moved than air molecules. (C) moving faster than air molecules. (D) larger than air molecules.
[A]: A


[Q]: A student adds water and detergent to a cup of soil. The mixture is shaken and allowed to settle. The student observes that silt particles stay suspended long after the other particles form layers at the bottom of the jar. The most likely explanation is that the silt particles are  
 (A) organic. (B) dissolving. (C) less dense. (D) moving faster.
[A]:
C