Read the text. Choose the best word that fits the space.
Despite these challenges, there is growing awareness in Russia about the need for environmental protection. Some efforts are being made to address these issues, such as the expansion of national parks, government initiatives to reduce industrial emissions, and reforestation programs. However, the scale of these efforts remains limited compared to the severity of the environmental problems the country faces. Addressing the environmental crisis in Russia requires stronger enforcement of regulations, investment in 6. ______ energy, and a shift towards more sustainable development practices.

• renewable
• recycling
• national
• physical