Test and analysis: gas is the "first killer" that threatens coal mine safety. The extracted gas is used to make it a clean and convenient energy source. When these key sentences are put together, the philosophy reflected in the material is obvious. BC is not reflected in the material, and D is wrong, because consciousness is right or wrong. It cannot be said that consciousness has played a positive and dynamic role in the development of things. The correct answer is a.

Comments: Candidates should be good at extracting key sentences and keywords from a large number of materials. As long as the key sentences and words are found accurately, the answer is basically not wrong. If you set a few key sentences or words, the answers are basically wrong. This requires candidates to have a deep understanding and accurate memory of knowledge points.