Utilize Databricks' file I/O capabilities for the CSV file and set up a separate cluster for the streaming data, ensuring isolation but potentially increasing complexity and cost.

Import the entire CSV file into a Databricks Delta table and attempt to use it as the sole source for processing both batch and streaming data, risking inefficiency and scalability issues.

Develop a custom solution to pre-merge the CSV and streaming data before processing, which may introduce delays and require significant maintenance.

Employ Databricks' integrated support for Delta and Structured Streaming to concurrently process the CSV file and real-time streaming data, leveraging built-in optimizations for performance and scalability.