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: After a star runs out of most of its hydrogen fuel, it becomes hotter and more luminous. What stage does this represent in the life cycle of a star?  
 (A) quasar (B) protostar (C) red giant (D) white dwarf

A: C
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Q: Joann repeatedly overfed the fish in the pond behind her house. The nitrates from the excess food contributed to an overgrowth of algae. To correct the problem, Joann added more plants to the pond. How will adding more plants help?  
 (A) The plants make the pond look beautiful. (B) The plants will camouflage the green algae. (C) The plants will compete with algae for nutrients. (D) The plants will provide all the food for the fish.

A: C
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Q: Radioactive waste from nuclear power plants is sealed in containers and deeply buried in the ground. Sealing and burying waste reduces the chances that water will become contaminated. At which point in the water cycle would radioactive contamination most likely be found?  
 (A) rain (B) fog (C) groundwater (D) surface water

A:
C
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