Final answer:
A plant's unplanned impact on the environment may include hazardous liquids contaminating groundwater, leading to various health problems and environmental degradation.
Step-by-step explanation:
An example of an unplanned impact that a plant may have on the environment is b. hazardous liquids leaking into groundwater. This can happen due to accidents or poor management practices at facilities such as petrol filling stations or from over-application of fertilizers in agriculture. When hazardous substances leak into groundwater, they can cause significant environmental damage, including pollution of drinking water supplies, which can lead to a myriad of health issues such as endocrine disruption, birth defects, and the spread of diseases. The use of plants in bioremediation is a method to mitigate such impacts, with practices such as planting species that can extract toxic metals from soils.