The regulation mandates that sensitive information cannot be stored on an ephemeral disk, which rules out the default Cloud Shell storage. Option A suggests using the Cloud Shell home disk, which is persistent but requires manual intervention to prevent deletion, making it less reliable for sensitive data. Option B, storing data on a persistent disk in a Compute Engine instance, provides durability but involves more complex setup and management. Option D, BigQuery, is designed for analytics and not suitable for general data storage. Option C, storing user data in a Cloud Storage bucket, is the most appropriate solution as it offers durability, scalability, and requires minimal code changes, aligning with the requirement to minimize code changes while complying with the new regulation.