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.

Example Input: Estuaries are marine environments located in areas where fresh water from rivers flow into the ocean. Estuaries are one of the most biologically productive ecosystems. Birds, fish, turtles and many other organisms inhabit these ecosystems. Which will most likely cause changes to estuary habitats on a global scale?  
 (A) decreases in powerful hurricanes (B) decreases in volcanic eruptions (C) increases in earthquakes (D) increases in sea level
Example Output: D

Example Input: A movie studio will use two methods of communication, television and the Internet, to advertise a new movie. Which of the following must both methods of communication use in order to show the advertisements to viewers around the world?  
 (A) systems to locate viewers (B) networks to transmit signals (C) printing to create the images (D) software to search for images
Example Output: B

Example Input: Sodium (Na) and chlorine (Cl) are two reactive and dangerous elements. Chlorine is a halogen gas that can cause respiratory damage and sodium is an alkali metal that reacts violently with water. What happens to the properties of sodium and chlorine when they react to form sodium chloride (NaCl), common table salt?  
 (A) The properties of both sodium and chlorine change. (B) The properties of both sodium and chlorine remain the same. (C) The properties of sodium are different but chlorine remains a dangerous gas. (D) The properties of sodium remain the same but the properties of chlorine change.
Example Output:
A