The correct answer is C. Methane and Air.
Methane is a colorless, odorless, and flammable gas that is found in natural gas and coal mines. When methane is mixed with air, it can form an explosive mixture. If a spark or flame ignites the mixture, it can cause a mine explosion.
Oxygen is a colorless, odorless, and tasteless gas that is essential for combustion. When oxygen is mixed with methane, it can increase the risk of a mine explosion.
Acetylene is a colorless, flammable gas that is used in welding and cutting. When acetylene is mixed with oxygen, it can form a highly explosive mixture. However, acetylene is not typically found in mines, so it is not a major cause of mine explosions.
Carbon dioxide is a colorless, odorless, and tasteless gas that is heavier than air. It is not flammable, but it can displace oxygen in the air, which can make it difficult to breathe. Carbon dioxide is not a major cause of mine explosions.
In conclusion, the correct answer is C. Methane and Air.