A Transaction Manager ensures ACID (Atomicity, Consistency, Isolation, Durability) properties in database transactions. It manages concurrent transactions, ensuring no conflicts occur and logs modifications to support recovery mechanisms.

Option A (Incorrect): Query optimization is managed by the query processor, not the transaction manager.

Option B (Incorrect): The transaction manager is a component of the database architecture but is not composed of the entire system (query processor, storage manager, etc.).

Option C (Correct): The transaction manager logs transactions like INSERT, UPDATE, and DELETE, ensuring consistency and recoverability.

Option D (Incorrect): The storage manager is responsible for translating queries into file system commands.