Ozone at the higher level of the atmosphere is a product of ______ acting on oxygen molecules.

UV radiation

The correct answer is option 3. UV radiation.

Ozone at the higher level of the atmosphere is a product of UV radiation acting on oxygen molecules.

UV (Ultraviolet) radiation from the sun interacts with oxygen molecules \((O_2)\) in the upper atmosphere, particularly in the stratosphere. This interaction causes the oxygen molecules to split into two oxygen atoms \((O)\), which then combine with other oxygen molecules to form ozone \((O_3)\). This process is known as the ozone-oxygen cycle.

The ozone layer, primarily located in the stratosphere, plays a crucial role in absorbing and filtering out harmful UV radiation from the sun, thus protecting life on Earth from excessive exposure to UV rays.