The correct sentence is A) My car is old and gets bad gas mileage. Having bad gas mileage is an ongoing thing that will never change unless you get a different car, so none of the other choices make sense.
Ethos. It establishes credibility because of the position of the political activist.
The writer's world is another way of saying; "The scene that is being set for the story to be told. Time, Location, Characters, Mood, Situation, etc.
For example, If you were telling a story about Dungeons and Dragons, perhaps you would mention that the main characters, Corlon, a Fighter and Esmerelda, a Sorceress are Trapped in a Dragon's Cave guarded by a Large one-eyed Cyclops and a Very Large Hungry Green Dragon. And so on.
Simple and direct, kind of like it sounds. Short and to the point.
Hope this helped!