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.

Q: The endangered Florida manatee is a large, aquatic mammal that feeds on sea grasses in brackish water. Due to where they like to feed, manatees are vulnerable to injuries from boat propellers. If speed zones requiring boats to maintain a low speed are placed in areas where manatees are known to congregate, which will most likely occur?  
 (A) less water pollution in manatee habitats will occur (B) manatees will seek alternate food sources (C) new manatee predators will surface (D) manatee populations will increase

A: D
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Q: When do mutations help make an ecosystem more sustainable?  
 (A) when mutations decrease the number of individuals in an ecosystem (B) when mutations increase the number of individuals in an ecosystem (C) when mutations decrease the number of species in an ecosystem (D) when mutations increase the number of species in an ecosystem

A: D
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Q: The excessive use of nitrogen-based fertilizers causes runoff that increases the nitrogen content of lakes and bays. These nitrogen compounds directly affect the aquatic ecosystems by  
 (A) interfering with the water cycle. (B) decreasing the predator population. (C) increasing the rate of algae growth. (D) causing aquatic animals to grow larger.

A:
C
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