Define sustainability in the context of energy usage.

Sustainability in the context of energy usage refers to the ability to meet current energy needs in a way that does not compromise the ability of future generations to meet their own energy requirements. This definition emphasizes the importance of balancing present energy consumption with the preservation of resources and the environment for the future. It incorporates the concepts of intergenerational equity and the responsible use of finite resources.

This perspective on sustainability ensures that energy systems are not only efficient but also accountable, encouraging the development and adoption of practices that safeguard ecological systems, reduce pollution, and conserve natural resources. It advocates for a conscious approach to energy consumption, where current demands are met without depleting or degrading the energy resources available for future use.

In contrast, the other options do not capture the holistic essence of sustainability. While energy-saving appliances and reliance on renewable resources can contribute to sustainability, they do not encompass the broader concept of ensuring future generations can also meet their energy needs. Disregarding future energy sources directly opposes the principles of sustainability, as it leads to the depletion of resources and environmental harm. Therefore, the answer that best encapsulates the definition of sustainability in energy usage is the ability to meet present energy needs without compromising future generations.