The right answer is "D. He believes more port activity would be good for Atlanta's business, too."
The explanation for this answer is in the mayor's own speech that appears in this question. Reed literally says: "Work can now begin in earnest on the Savannah Harbor Expansion Project, bringing with it significan economic benefits to the entire state of Georgia ..." This is because he hoped to strengthen the city, economically, thus bringing more jobs and quality of life to citizens.