The correct answer is option 2: Green-house gas. Green-house gases are responsible for the phenomenon known as the greenhouse effect, which is essential for sustaining life on Earth but becomes problematic when their concentration increases.

When heat rays are reflected from the Earth`s surface, certain gases in the atmosphere, such as carbon dioxide (CO2) and nitrous oxide (N2O), trap and absorb some of the heat. Instead of allowing the heat to escape back into space, these gases prevent it from leaving, causing the Earth`s temperature to rise. This is similar to how a greenhouse works, hence the term "greenhouse effect."

Noble gases (option 1) are a group of chemical elements found in the atmosphere, including helium, neon, argon, krypton, xenon, and radon. However, noble gases do not play a significant role in trapping heat or causing the greenhouse effect.

Option 3 (Hot gas) and option 4 (Blue gas) are not accurate descriptions of the gases in question. Hot gas is a general term and does not specifically refer to greenhouse gases, and there is no specific type of gas referred to as blue gas.

In summary, option 2, Green-house gas, is the correct answer as it accurately