The presence of ozone in the atmosphere is important because it absorbs ultraviolet-B (UV-B) radiation. UV-B radiation is a type of solar radiation that has shorter wavelengths than visible light. It is known to cause various harmful effects on living organisms, including damage to DNA, skin cancer, and damage to ecosystems.

Option 1 states that ozone absorbs both ultraviolet-A (UV-A) and UV-B radiations. UV-A radiation has longer wavelengths and is less harmful compared to UV-B radiation. Although ozone does absorb some UV-A radiation, it is not its primary purpose.

Option 3 suggests that ozone absorbs only infrared-B (IR-B) radiations. However, this is incorrect. IR-B radiation is a type of infrared radiation and is not related to the absorption of ozone.

Option 4 states that ozone absorbs both outgoing UV-B radiation and incoming UV-A radiation. This is not entirely accurate. While ozone does absorb some UV-A radiation, its main role is to absorb UV-B radiation.

Therefore, the correct answer is option 2, which states that ozone absorbs UV-B radiations only.