Long Beach is the California city listed as a Dexter production location besides Miami. Although the story is set in Miami, Florida, much of the series was filmed in Southern California, using Los Angeles and Long Beach locations to create its Florida setting.
Long Beach supplied recognizable exteriors and interiors throughout the production. Locations included landmarks such as the Villa Riviera and the Abbey San Encino. California State University, Long Beach also appeared prominently, particularly in season six, when several campus buildings represented settings connected to the Doomsday Killer storyline.
This distinction is important because Dexter’s fictional geography and its real filming geography are different. Miami is the setting of the story, while Long Beach is one of the principal places used to shoot the show. Ontario International Airport in Ontario, California, was also used for a finale airport scene.
The other choices—Oakland, Sacramento, and San Diego—are California cities, but they are not the listed answer for this production-location question.