Similarity search in Oracle 23ai (C) uses vector embeddings in VECTOR columns to retrieve entries semantically similar to a query vector, based on distance metrics (e.g., cosine, Euclidean) via functions like VECTOR_DISTANCE. This is key for AI applications like RAG, finding “close” rather than exact matches. Optimizing relational operations (A) is unrelated; similarity search is vector-specific. Exact matches in BLOBs (B) don’t leverage vector semantics. Grouping by scores (D) is a post-processing step, not the primary purpose. Oracle’s documentation defines similarity search as retrieving semantically proximate vectors.