What is the MOST likely reason Reed would support such a project

I believe the answer is: He believes more port activity would be good for Atlanta's business, too

Atlanta Major Kasim Reed see that port activities provide chance for people from outside atlanta had an access to the market in atlanta and vice versa. This provide many business opportunitites for people in atlanta and would positively influence atlanta's economy.

D) He believes more port activity would be good for Atlanta's business, too.