The correct answer to the question is option 3 - Stratosphere.

Ozone is a gas molecule made up of three oxygen atoms (O3) and it plays a crucial role in the Earth`s atmosphere. The Earth`s atmosphere is divided into different layers based on altitude, and the layer where most of the ozone is found is called the stratosphere.

The stratosphere is located above the troposphere, the lowest layer of the atmosphere. It extends from about 10 kilometers to 50 kilometers above the Earth`s surface. The stratosphere contains approximately 90% of the ozone in the atmosphere.

The presence of ozone in the stratosphere is important because it helps to absorb a significant amount of the Sun`s harmful ultraviolet (UV) radiation. This UV radiation can cause damage to living organisms, including humans, such as skin cancer and cataracts.

It is important to note that ozone is also found in other layers of the atmosphere, such as the troposphere, mesosphere, and ionosphere. However, the majority of ozone is concentrated in the stratosphere.