Encrypting data before it leaves the organization is the best way to protect sensitive data from administrators within a public cloud, as it ensures that the data is secured at the source and remains encrypted throughout the transmission and storage in the cloud. Using an encrypted tunnel to connect to the cloud, encrypting the data in the cloud database, and encrypting physical hard drives within the cloud are not the best ways, as they may not prevent the cloud administrators from accessing the data or the encryption keys, or may not protect the data from unauthorized interception or modification during the transmission. References = CRISC Review Manual, 7th Edition, page 153.