Final answer:
Modern houses are more energy-efficient due to design features that conserve energy but also have higher levels of indoor pollution due to reduced ventilation and pollutant-emitting materials and appliances.
Step-by-step explanation:
Modern houses are designed to be more energy-efficient, but as a result, they often have higher levels of indoor pollution. Factors contributing to this include tighter sealing of buildings, which helps to conserve energy on heating and cooling, but also traps pollutants inside. Moreover, materials and appliances within modern homes can release a range of pollutants, such as volatile organic compounds from paints and furniture, or carbon monoxide from combustion appliances.
Efforts to improve energy efficiency in homes, like adding insulation or using double-paned windows, also contribute to reduced air exchange with the outdoor environment. While this is beneficial for reducing energy consumption and lowering carbon footprints, it can lead to an accumulation of pollutants inside the home unless proper ventilation measures are in place. In addition, modern homes can employ environmentally friendly technologies like solar panels and energy-efficient appliances to reduce reliance on fossil fuels.
Answer: B. Energy-efficient