Which of the following is the BEST way to ensure data is not co-mingled or exposed when using a cloud service provider?

Requiring the cloud service provider to follow stringent data classification procedures is the best way to ensure data is not co-mingled or exposed because it mandates that the provider categorizes and handles data according to its sensitivity, leading to appropriate segregation, access controls, and protection mechanisms. This proactive approach ensures that data is logically or physically separated and protected based on its classification, directly preventing unauthorized mixing or exposure.

Obtaining an independent audit report provides assurance about the provider's overall controls, but it's a backward-looking assessment and doesn't directly ensure specific operational procedures like data classification are being followed daily for your data.

Reviewing the provider's information security policies helps understand their stated approach, but does not guarantee the rigorous implementation of those policies or their effectiveness in preventing co-mingling and exposure.

Including high penalties for security breaches in the contract provides legal recourse after an incident, but it does not proactively prevent data co-mingling or exposure in the first place.