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: Campers shouted toward a canyon wall. What characteristic of sound best explains why the campers heard an echo?
(A) Sound waves traveled slowly down the canyon. (B) Sound waves were absorbed by the canyon wall. (C) Sound waves reflected off the canyon wall. (D) Sound waves were refracted around the canyon.

A: C
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Q: For a technology project, Kyle came up with an idea to build a model bridge. He wants his bridge to span 50 cm and to support a 1 kg object. According to the engineering design process, which of the following should be Kyle's next step?
(A) construct prototypes of different kinds of bridges (B) research the different designs of bridges (C) gather the materials needed to build the bridge (D) make a drawing to show how to build the bridge

A: B
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Q: Which energy source might involve burning wood or producing gasohol?
(A) biomass (B) wind turbine (C) nuclear fission (D) hydroelectric power

A:
A
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