What is the ACID property of transactions in a database system, and how does it ensure data consistency?

$($a$)$ Atomicity: Transactions are indivisible units of work, ensuring all operations are completed or none are. $($b$)$ Consistency: Ensures the database remains in a valid state after a transaction. $($c$)$ Isolation: Transactions are isolated from each other, preventing conflicts. $($d$)$ Durability: Changes made by a transaction are persisted permanently.