I would think its D. because in the story "Letter to the editor" How are mixed-use areas different from what we have now? Let me tell you. Our city currently has a dense downtown area and then a massive amount of sprawl reaching out in every direction—the sprawl takes up seventy-five percent of the city’s land. Urban sprawl, the spreading of large developments of housing and shopping areas around a city’s center, has many negative cultural and environmental effects. Sprawl increases traffic congestion along highways. The residents who live in these faraway suburbs often work downtown, where the majority of businesses are still located. They have to undertake long commutes to and from work every day, which limits their time with family and friends and increases their time alone on the road. These longer commutes also result in increased air pollution that can lead to smog problems for the city.
'Exert' means to apply force on influence over something else, this can be in a negative or positive way. In this quotation, it means that language, if used correctly, has the ability to express a 'hidden power'. It's also worth mentioning that the simile is relevant as the moon has an influence on the level of tides on Earth.
