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: A delta can be seen from the air at the mouth of the Mississippi River. This delta was formed by  
 (A) erosion. (B) weathering. (C) conservation of soil. (D) deposition of sediment.

A: D
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Q: Which best describes a scientific theory?  
 (A) It is still being tested. (B) It is true, once written. (C) It is different for each continent. (D) It is determined in a court of law.

A: A
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Q: A euglena has a flagellum and a paramecium has cilia. Both types of organelles help these organisms move through the water. However, a paramecium can also use its cilia to perform another task. What is this task?  
 (A) obtain food (B) defend the cell (C) attach to a surface (D) perform conjugation

A:
A
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