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]: 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
[A]: D


[Q]: All planets of the solar system rotate, but not all planets have the same rotational velocity. Which characteristic of a planet is determined by the rotational velocity of the planet?  
 (A) the strength of the gravity (B) the shape of the orbit (C) the size of the planet (D) the length of the day
[A]: D


[Q]: Which substance would most neutralize an acidic food?  
 (A) dairy(pH 5-7) (B) water (pH 6-7) (C) citrus fruit (pH 2-3) (D) baking soda (pH 8-9)
[A]:
D