What key benefit does watsonx.data's shared metadata layer provide when multiple engines query the same table?

watsonx.data's unified metadata catalog ensures Presto; Spark; and other engines all reference the same table definitions and data files; eliminating the need to copy or duplicate data for different workloads. The incorrect options ("Each engine maintains its own copy of the data for independent optimization", "The metadata layer automatically migrates data between engines based on access frequency", "Shared metadata enables a single engine to process all queries regardless of type") are distractors that don't fully capture the concept described.