Marine oil pollution occurs when crude oil or refined oil products are accidentally or deliberately released into the ocean — for instance, through tanker accidents, leaks from offshore drilling platforms and pipelines, ballast water discharge, or spills during loading/unloading at ports.

Why petroleum products are the associated pollutant group:

• Oil spills consist of petroleum products: crude oil and its refined derivatives such as diesel, gasoline, kerosene, and other hydrocarbon fractions, all of which are immiscible with (do not mix into) water and less dense than seawater.
• Because these hydrocarbons float and spread rapidly across the sea surface, they form a thin oil slick that can cover very large areas within hours of a spill.

Environmental effects of oil spills:

• The slick blocks sunlight penetration, disrupting photosynthesis by phytoplankton and marine plants, and also interferes with the natural exchange of oxygen between air and water, lowering dissolved oxygen levels.
• It physically coats the feathers of seabirds and the fur of marine mammals, destroying their natural insulation and buoyancy, often leading to hypothermia and drowning.
• Toxic components of the oil directly poison fish, coral reefs, plankton, and other marine organisms, and can persist in sediments and food chains for years after the initial spill.
• Clean-up is difficult and often only partially effective, meaning ecological damage from a major spill can take a long time to fully recover.

Because the pollutant discharged in these events is specifically crude oil and its hydrocarbon derivatives, the correct answer is petroleum products.

Why the other options are incorrect:

• Chemical fertilizers are nutrient compounds (containing nitrogen, phosphorus, etc.) that typically run off agricultural land into rivers and lakes, causing eutrophication — they are not associated with oil spills.
• Synthetic detergents, when discharged from domestic or industrial wastewater, also contribute to eutrophication and foaming in water bodies, but they are unrelated to the hydrocarbon pollution caused by oil spills.
• Agricultural pesticides reach water bodies mainly through surface runoff from farmland and contaminate soil and freshwater systems; they are a distinct pollutant category from the petroleum hydrocarbons released in ocean oil spills.