The correct option is Carbon dioxide.
Explanation
The Earth receives energy from the Sun primarily as shortwave radiation, which passes relatively freely through the atmosphere. The Earth's surface then re-emits this energy as longwave (infrared) radiation. Certain gases in the atmosphere, known as greenhouse gases, are transparent to incoming shortwave radiation but absorb outgoing longwave radiation, trapping heat in the lower atmosphere.
- Nitrogen Nitrogen and Oxygen Oxygen: These are the two most abundant gases in the atmosphere, comprising approximately 99% of its volume. They are diatomic molecules that are largely transparent to terrestrial longwave radiation and do not significantly contribute to the greenhouse effect.
- Carbon Dioxide Carbon dioxide: Carbon dioxide is meteorologically a very important gas. It is transparent to the incoming solar radiation (shortwave) but opaque to the outgoing terrestrial radiation (longwave). It absorbs a part of this terrestrial radiation and reflects some of it back towards the Earth’s surface, playing a crucial role in the heating of the atmosphere.
- Argon Argon: Argon is an inert noble gas constituting about 0.93% of the atmosphere. It does not absorb infrared radiation and has no significant role in the Earth's heat budget.
Key Takeaway: Carbon dioxide is the primary gas among the major atmospheric constituents responsible for the greenhouse effect because it selectively absorbs longwave radiation emitted by the Earth while allowing shortwave solar radiation to pass through.