The correct option is (c) 1 and 3 only.
Explanation
The ozone layer is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet (UV) radiation. It contains a high concentration of ozone ($O_3$) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere.
Statement 1 is Correct: The ozone layer is primarily situated in the lower portion of the Stratosphere, approximately 15 to 35 kilometers above Earth's surface. The thickness of the ozone layer varies seasonally and geographically.
Statement 2 is Incorrect: The fundamental function of the ozone layer is to absorb the majority of the Sun's harmful ultraviolet radiation (specifically UV-B and UV-C). By doing so, it prevents these harmful rays from reaching the Earth's surface, thereby protecting living organisms from health risks such as skin cancer and cataracts.
Statement 3 is Correct: Ozone depletion is primarily caused by human-made chemicals known as Ozone-Depleting Substances (ODS). Chlorofluorocarbons (CFCs) are a major category of ODS. When CFCs reach the stratosphere, ultraviolet radiation breaks them down, releasing chlorine atoms which then catalytically destroy ozone molecules.
Key Takeaway: The ozone layer is located in the Stratosphere and acts as a protective shield by absorbing harmful UV radiation. Its depletion is driven by synthetic chemicals like CFCs.