The correct answer is: a) Eutrophication.
Excessive use of pesticides and fertilizers can lead to eutrophication, which is the process by which an aquatic ecosystem becomes enriched with nutrients. This can cause an increase in the growth of algae and other aquatic plants, which can lead to a decrease in dissolved oxygen levels in the water. This can have a negative impact on aquatic life, and can also make the water unsafe for human consumption.
Soil salinity is the buildup of salts in the soil. This can be caused by a number of factors, including excessive irrigation, the use of saline water, and the application of fertilizers. Soil salinity can have a number of negative impacts on plant growth, including reduced crop yields, increased susceptibility to pests and diseases, and changes in the composition of plant tissues.
Air pollution is the contamination of the air by harmful substances. This can be caused by a number of sources, including emissions from vehicles, power plants, and industrial facilities. Air pollution can have a number of negative impacts on human health, including respiratory problems, heart disease, and cancer.
Deforestation is the clearing of forests for other uses, such as agriculture, development, or logging. This can have a number of negative impacts on the environment, including soil erosion, loss of biodiversity, and climate change.
In conclusion, the correct answer is: a) Eutrophication.