Final answer:
Plan B is an example of sustainable development as it seeks to balance human transportation needs with preserving forest ecosystem services for future generations.
Step-by-step explanation:
Among the two plans for building a new highway through a tract of forest in Arbordale, Plan B is an example of sustainable development. Sustainable development is a method of resource use that aims to meet human needs while preserving the environment so that these needs can be met not only in the present, but also for future generations. Plan B, although less efficient and potentially less safe for motorists, prioritizes the protection of the forest and its ecosystem services. It attempts to balance human transportation needs with the long-term preservation of natural habitats, making it a more sustainable choice than Plan A, which prioritizes immediate human needs over environmental considerations and would cause habitat fragmentation and water supply pollution.