What is the fine-grained topic of the following text: Since 2011, the San Diego Energy District (SDED) has been a strong, vocal and single-focus advocate for the creation in San Diego of a "Community Choice Aggregation" (CCA), a vehicle under California State law that allows municipalities to choose cleaner and cheaper electricity for residents and businesses. Only return the topic.
San Diego Energy District's advocacy for Community Choice Aggregation in San Diego