You are given a science question (hard-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: Laura adds 50 mL of boiling water to 100 mL of ice water. If the 150 mL of water is then put into a freezer, at what temperature will the water freeze?  
 (A) 0°C (B) 15°C (C) 37°C (D) 50°C

A: A
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Q: Nectar is a sweet liquid that some flowering plants produce. A hummingbird drinks nectar from a flower. When a hummingbird drinks nectar, pollen from the flower sticks to the hummingbird's beak. The picture shows a hummingbird drinking nectar from a flower. Which statement explains the role of a hummingbird in the life cycle of a flowering plant?  
 (A) A hummingbird carries food to the plant. (B) A hummingbird helps the plant reproduce. (C) A hummingbird protects the plant from predators. (D) A hummingbird makes the flowers produce nectar.

A: B
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Q: Which type of rock forms by weathering?  
 (A) igneous rock (B) extrusive rock (C) sedimentary rock (D) metamorphic rock

A:
C
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