D. It's used to create grassroots support for oil spills, dirty water, and polluted air. To encourage one to think globally and act locally typically means that one should consider the issues that exist in the world and to begin to make a difference by taking action in his or her community because in order to change the world, it is believed, one should first change his or her immediate surroundings because that is where it all starts—change. Further, it is meant to convey the idea that nothing environmental is mutually exclusive because everything is connected on this planet because of the ripple effect of even the smallest of actions. It encourages one toward believing in the idea that everyone can make a difference in so much that what is globally occurring more often than not started locally somewhere—it has its “grassroots.” Thus, the appropriate response is D. It's used to create grassroots support for oil spills, dirty water, and polluted air.