Answer: C. Harm to marine life and disruption of ecosystems.
Explanation: Oil spills are known for causing harm to marine life. Oil is composed of many toxic compounds that can stunt growth and harm the health of marine life. It can remove the waterproofing nature of fur and feathers, leaving marine birds and mammals to freeze to death from hypothermia. Oil also reduces plant transpiration and photosynthesis, reducing the amount of energy availiable in the producer trophic level of the marine ecosystem.
Therefore, answer choice C is the primary environmental concern for oil spills. Since oil spills occur in the water and not in the air or on land, answer choices a, b, and d are not primary concerns for oil spills.