Understanding Transaction Properties
In the context of database management systems, transactions are crucial for ensuring data integrity and consistency. The key properties of transactions are often summarized by the acronym ACID, which stands for Atomicity, Consistency, Isolation, and Durability.

Key Properties of Transactions
- Atomicity:
This property ensures that a transaction is treated as a single unit of work. It either completes fully or does not happen at all. If any part of the transaction fails, the entire transaction is rolled back, maintaining the database's integrity.
- Isolation:
Isolation ensures that transactions execute independently of one another. Even if transactions are occurring simultaneously, the outcome should not be affected by the concurrent execution of other transactions, preventing data inconsistency.
- Durability:
Once a transaction has been committed, it remains so, even in the event of system failures. This ensures that completed transactions are not lost and that the database reflects all committed transactions fully.

Why Symmetricity is Not a Property
- Symmetricity:
This term does not relate to transaction properties in databases. It refers to a concept in mathematics and computer science dealing with symmetry and balance, which is not applicable to the ACID properties of transactions.
In conclusion, while Atomicity, Isolation, and Durability are essential properties of transactions, Symmetricity is not relevant in this context, making it the correct answer to the question.