Minimize cost and effort to verify uploaded Cloud Storage objects match on‑premises files.

The correct answer minimizes cost and effort by leveraging gsutil's built-in CRC32C hashing. When files are uploaded to Cloud Storage, a CRC32C checksum is automatically computed and stored as metadata. gsutil hash -c efficiently calculates the CRC32C of local files, and gsutil ls -L retrieves the stored CRC32C for uploaded objects. Comparing these hashes directly verifies data integrity without re-downloading or complex custom tools. Option 1 is inefficient as it involves re-downloading all uploaded files and recomputing shasums, increasing network egress costs and time. Option 2 requires developing and maintaining a custom Java tool, adding development and operational overhead. Option 3 is highly inefficient and costly, as it downloads all files and performs a byte-by-byte comparison, incurring significant egress charges and processing time.