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: The teacher heats a pot of water. Once the water reaches 100°C, which point has the water reached?  
 (A) boiling (B) melting (C) freezing (D) evaporating

Answer: A


Question: Which of the following best describes a mineral?  
 (A) a solid natural material with a crystal structure (B) a material that was once living but has decayed (C) a liquid chemical used to make soil more fertile (D) a nutrient produced by plants that other organisms need

Answer: A


Question: Scientists studying migrating birds and homing pigeons have discovered that they navigate by monitoring differences in the intensity and inclination of Earth's magnetic field. Special cells in bird beaks can detect these changes as the birds fly over Earth's surface. Which metal did the scientists find in the cells that birds use as a magnetometer?   
 (A) iron (B) gold (C) mercury (D) aluminum

Answer:
A