Concept:Oil spills occur when liquid petroleum is released into the environment, most often in oceans and seas due to human activities.Explanation:Oil spills happen from sources like tankers, drilling rigs, offshore platforms, and pipelines. This pollution harms marine life, coastlines, and local economies. Desert, grassland, and forest ecosystems are not the primary locations for such spills because oil extraction and transport largely take place in or near water bodies. Hence, the marine ecosystem is where oil spills are commonly seen.Answer:D. Marine ecosystem