What is the city code for San Francisco, California?

The city code for San Francisco, California, is SFO. This code is derived from the airport's name, San Francisco International Airport, which is the primary airport serving the city. SFO is designated by the International Air Transport Association (IATA) and is widely recognized in travel and aviation contexts.

In contrast, the other options correspond to different cities or airports. SAC is the code for Sacramento, California, which is the state capital but not related to San Francisco. SAN is the code for San Diego International Airport, located in Southern California, while SEA is the code for Seattle-Tacoma International Airport in Washington state. Each of these codes serves a different geographic area, making SFO the correct answer for San Francisco.