San Francisco is known for the colorful murals painted on many of its buildings. The densest collection of murals is found on Balmy Alley in the Mission District neighborhood. In the 1970s, Latina artists painted vivid scenes of community life on walls along this block. As the original murals have faded, later generations of artists have painted new ones over them. As a result, Balmy Alley has become a living showcase of San Francisco's artistic spirit, with its murals reflecting changes in the cultural life of the city.

Which choice best states the main purpose of the text?