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.

[EX Q]: A student plans to design a new toothpaste tube that will give the same amount of toothpaste every time it is squeezed. Which should the student do first when designing the new tube?  
 (A) make a data table of amounts of toothpaste (B) gather building materials (C) create models of old toothpaste tubes (D) draw a few possible solutions
[EX A]: D

[EX Q]: Which of these objects is translucent?  
 (A) A student's notebook (B) A mirror on the bus (C) A brick wall of the school (D) A student's sunglass lenses
[EX A]: D

[EX Q]: How are sedimentary rocks made?  
 (A) Magma or lava is cooled. (B) Materials are pressed together. (C) Chemical reactions change minerals. (D) Earthquakes cause small pieces to fall.
[EX A]:
B