The correct answer for the occurrence of photochemical smog is option 2, which is a warm, dry, and sunny climate.

To understand why option 2 is correct, let`s break down the different factors involved in the formation of photochemical smog. Photochemical smog is a type of air pollution that is formed when sunlight reacts with pollutants in the air, such as nitrogen oxides (NOx) and volatile organic compounds (VOCs).

In a warm climate, the temperature is higher, which promotes the chemical reactions between NOx and VOCs. Additionally, the sun`s ultraviolet (UV) radiation is stronger in a sunny climate, further enhancing the photochemical reactions.

Dry conditions are also favorable for the formation of photochemical smog because moisture in the air can interfere with the reactions and reduce the concentration of pollutants.

On the other hand, cool and humid climates (option 1) have lower temperatures and higher moisture levels, which are not conducive to the formation of photochemical smog. Option 3, a cool, dry, and sunny climate, doesn`t favor the chemical reactions necessary for photochemical smog. Finally, option 4, a warm and humid climate, doesn`t include the dry condition required for the