The Clue East coast : NY :: ___ coast : SFO
The Answer WEST
The clue compares two locations: New York (NY) on the East Coast and San Francisco (SFO) on the West Coast. Just as New York is on the east side of the United States, San Francisco is located on the west side. Therefore, the answer "WEST" fits perfectly, as it describes the direction of the coast where San Francisco is found. This creates a clear relationship between the two pairs of locations.