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.
--------
Question: During a biochemical reaction, pyruvate (C3H4O3) is converted into carbon dioxide (CO2) and water (H2O). In what cellular organelle does this biochemical reaction occur?
(A) nucleus (B) cytoplasm (C) mitochondria (D) endoplasmic reticulum

Answer: C

Question: Sharpening a pencil and tearing paper are examples of physical changes. Which statement describes why these are physical changes?
(A) There is a change in how the objects are used. (B) There is a change in the appearance of the objects. (C) There is a change in the materials from which the objects are made. (D) There is a change in both the appearance of the objects and the materials from which they are made.

Answer: B

Question: Some changes are fast. Some changes are slow. Which of these changes is most likely the slowest?
(A) fire (B) flood (C) landslide (D) drought

Answer:
D