Geography as an integrating discipline

Factory production may create private income and goods, but smoke imposes health risks and possible medical costs on nearby residents who did not choose the transaction. Because the outside effect is harmful rather than beneficial, it is a negative environmental externality. A positive externality would provide an unintended benefit, while the other options are not classifications of this impact.

An urban park can improve air quality, reduce local heat and offer recreation to people who may not own or manage the park. These benefits spill over to surrounding residents and are not necessarily fully paid for through a market transaction. Since the external effect is beneficial, it is a positive externality. The other options describe different conditions.

Resources are limited, so choosing one use means giving up at least one alternative. Opportunity cost is the value of the best alternative forgone, not every possible alternative and not merely the money paid. If a forest is used for mining, lost conservation, livelihood or ecosystem benefits may form part of the opportunity cost. Thus A states the correct economic idea.

A social-ecological system includes people, institutions, technologies, resources and ecological processes as interacting parts. Communities depend on ecosystems for water, food and livelihoods, while human decisions alter those ecosystems. Laws, property arrangements and local knowledge also influence resource use. Therefore society and nature cannot be analysed as separate, independent spheres. A expresses this integrated approach.

Urban trees provide several services at once. Their shade and evapotranspiration can reduce local heat, leaves can help filter some air pollutants, and green spaces support recreation, mental well-being and habitat. The exact benefit depends on species, location and maintenance, but it is not limited to timber. Tree planting does not increase mineral availability or automatically make traffic faster, so A is correct.

The demand for soy in one country can influence production decisions, land prices and forest conversion in another country through international trade. The consumption and environmental change occur in different places, which is the defining feature of a distant human-environment connection. The other examples may involve environmental processes or local actions, but they do not clearly show a long-distance social link.

Virtual water is the water used throughout the production of a good, even though that water is not physically shipped with the final product. It may include irrigation, rainfall counted in production analysis, processing and other stages, depending on the accounting method. A water-intensive crop therefore carries a hidden water requirement through trade. A is correct; atmospheric vapour and bottled water are different concepts.

The polluter-pays principle requires the person or firm responsible for pollution to bear appropriate costs of prevention, control, cleanup or compensation. It aims to prevent firms from shifting environmental damage onto society and encourages cleaner production. The principle does not mean that every cost can always be recovered or that government has no role, but it rejects making affected communities pay for someone else’s pollution. Therefore A is correct.

Nature-based solutions protect, restore or manage ecosystems so that they address human challenges while also supporting biodiversity and ecological function. Restored mangroves can reduce coastal wave energy, wetlands can store floodwater and urban vegetation can lower heat. These approaches may be combined with engineered structures, but they are not simply concrete construction or vegetation removal. Therefore A gives the correct broad definition.