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.
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Question: 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

Answer: D


Question: Wolves have adapted skills for hunting large hoofed animals such as elk, deer, or moose. Wolves tend to target prey animals that are sick or weak. The wolf benefits from this strategy because it uses less energy to hunt. How would the prey animal population also benefit from this strategy?  
 (A) by promoting detrimental genes (B) by stimulating beneficial DNA mutations (C) by preventing the introduction of other predator species (D) by increasing the reproductive success of healthy prey animals

Answer: D


Question: Which is Earth's largest source of drinkable water?  
 (A) lakes (B) rivers (C) oceans (D) aquifers

Answer:
D