How should you optimize batch file transfers of game statistics into Cloud Storage for ETL staging?

For optimizing batch file transfers to Cloud Storage, using gsutil to copy files in parallel is the most efficient method. The 'gsutil -m cp' command enables parallel (multi-threaded/multi-processing) copies, significantly speeding up transfers of many small files or large files by splitting them into chunks. This maximizes throughput and minimizes transfer time, which is crucial for timely ETL staging. Moving files in sequence (option A) would be much slower, especially for large batches. Extracting files as the first part of ETL (option C) or loading them as the last part (option D) describes stages of the ETL process itself, not the optimized transfer method to get the data into Cloud Storage for staging.