Answer:
Amanda works for a business that helps make mass transit as
energy efficient as possible. - sustainability
Sustainability encompasses all the actions that regular businesses make in order to be more sustainable and protect the environment. Sustainability is not always as impactful as green jobs for environmental conservation but it can be so. Amanda works at a mass transit company that takes actions to be more sustainable.
Maria researches ways to conserve natural resources for the future - green jobs
Maria is working at a green job. A green job is one that contributes significantly to the environment, that revolves around it like Maria's job as a researcher does.
Jeff works for a restaurant that recycles and reuses all of its waste so that it produces virtually no waste. - sustainability
Jeff is working at a regular restaurant that does a lot for being more sustainable and for the environment as a whole. This is a sustainability job.