Gasoline was rationed during World War II because there were massive shortages due to the war effort. The U.S. Office of Price Administration issued a nationwide rationing in 1942 to assist in the war effort that ended in 1945. What was in shortage was rubber, not gasoline, and the best way to lower the rubber usage was to limit the amount of gasoline people could purchase to use in their cars.
I believe the answer is: A.a New York businessman who relocated to Mississippi
Carpetbagger refers to the people who are perceived to take advantage of unstable political situation in the country in order to obtain financial profit. The most likely people who called a carpetbagger are most likely businessman from northern states who tried to explain their influence on the southern states by bringing technological advancement.
The main point of the excerpt is that readers should be aware of the damage that the war has done to a generation of men who were impacted by it, and read the book with this idea in mind.
The epigraph wants to make sure that readers who approach this book do it with the same purpose as the one with which the author wrote it. He does not want the readers to think of this book as an accusation, a confession or an adventure.