Final answer:
The correct answer is A) Transparent Data Encryption (TDE), as it encrypts data at rest in Azure SQL Database and Azure Data Warehouse, protecting against unauthorized access.
Step-by-step explanation:
To protect Azure SQL Database and Azure Data Warehouse against the threat of malicious activity, Transparent Data Encryption (TDE) is the main feature used.
TDE helps protect against the threat of unauthorized access to data at rest by encrypting the databases, associated backups, and transaction log files at rest without requiring changes to the application.
Azure Storage Service Encryption and Azure Disk Encryption, while important for data security, do not directly protect the databases within Azure SQL Database or Azure Data Warehouse. Therefore, the correct answer to the question is A) Transparent Data Encryption (TDE).