A money transfer debits one account, and the system crashes before the matching credit is applied. Which ACID property requires that the debit be undone?
Correct answer A. Atomicity
Explanation
Atomicity means a transaction is all or nothing: either every operation takes effect or none does, so a half-finished transfer must be rolled back during recovery. Consistency is the related goal that the total balance remains correct, but atomicity is the property that enforces undoing the partial work. Durability concerns committed transactions, and this one never committed.
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