Correct Option (C)
I, II and III
Explanation
Statement I is correct. The Earth's atmosphere acts as a crucial insulating layer. Without its presence, the planet would experience rapid heat loss to space, leading to global surface temperatures significantly below the freezing point (0°C). This absence would also result in extreme diurnal (day-night) temperature fluctuations.
Statement II is correct. The atmosphere plays a vital role in regulating Earth's temperature through the natural greenhouse effect. It absorbs and traps outgoing longwave (infrared) radiation emitted from the Earth's surface, preventing it from escaping directly into space. This process maintains the planet's average surface temperature at approximately 15°C, making it habitable.
Statement III is correct. Certain atmospheric gases, known as greenhouse gases, are particularly efficient at absorbing and re-emitting longwave radiation. Key examples include carbon dioxide (CO₂), water vapour, methane (CH₄), and nitrous oxide (N₂O). Their ability to absorb this radiation is fundamental to the atmosphere's capacity to trap heat and influence global climate.
Incorrect Options
Options (1), (2), and (4) are incorrect because they omit at least one of the statements. All three statements provided are factually accurate regarding the essential role of the atmosphere and greenhouse gases in regulating Earth's temperature and maintaining its habitability.