The correct answer is C: Tri-secret secure encryption. This is Snowflake's specific term for the encryption method where a customer-managed key is combined with a Snowflake-managed key to create a composite master key for enhanced security. The community discussion consistently identifies C as the correct answer with 100% consensus, and multiple comments reference official Snowflake documentation that confirms this terminology. Option A (Hierarchical key model) refers to a general encryption key structure but not this specific composite key approach. Option B (Client-side encryption) involves encrypting data before it reaches Snowflake, not combining keys within Snowflake. Option D (Key pair authentication) relates to authentication mechanisms, not composite key encryption.