Which of the following materials drained from the crankcase is most harmful to the environment?

The most harmful materials drained from the crankcase are heavy metals and additives. Crankcase oil can contain a variety of contaminants that pose significant environmental hazards. Heavy metals such as lead, cadmium, and arsenic can accumulate in the soil and water systems, leading to toxicity in living organisms. These substances can persist in the environment for long periods, potentially entering the food chain and affecting animal and human health.

Additives in motor oil, which are designed to enhance performance or longevity, can also include harmful chemical compounds. When released into the environment, these additives can contribute to pollution and have detrimental effects on ecosystems, as they may interfere with biological processes or contribute to the degradation of water quality.

Other choices, while they can also pose environmental risks, do not present the same level of toxicity or long-term environmental impact as heavy metals and additives. For example, while organic solvents can be harmful, their effects are often more localized and less persistent compared to the lasting damage that heavy metals can inflict. Similarly, water and oil may create slicks and pollution but do not carry the bioaccumulative risks associated with heavy metals. Plastic waste is an environmental concern for its impact on wildlife and ecosystems but is less directly toxic compared to the chemical components found in