The correct answer is B. ozone.
Ozone is a gas that is found in the stratosphere, which is the second layer of Earth’s atmosphere. Ozone is made up of three oxygen atoms, and it is a very effective filter of ultraviolet light. Ultraviolet light can cause skin cancer and other health problems, so ozone is important for protecting living things from this radiation.
Helium is a gas that is found in the Earth’s atmosphere, but it is not found in the stratosphere. Helium is a very light gas, and it rises up into the atmosphere and escapes into space.
Oxygen is a gas that is found in the Earth’s atmosphere, and it is also found in the stratosphere. However, oxygen is not as effective at filtering out ultraviolet light as ozone is.
Methane is a gas that is found in the Earth’s atmosphere, but it is not found in the stratosphere. Methane is a greenhouse gas, and it contributes to climate change.
In conclusion, the gas present in the stratosphere which filters out some of the sun’s ultraviolet light and provides an effective shield against radiation damage to living things is ozone.