Which of the following scenarios may lead to an irrecoverable error in a database system?
- A. A transaction writes a data item after it is read by an uncommitted transaction
- B. A transaction reads a data item after it is read by an uncommitted transaction
- C. A transaction reads a data item after it is written by an committed transaction
- D. A transaction reads a data item after it is written by an uncommitted transaction
Answer: D. A transaction reads a data item after it is written by an uncommitted transaction
Explanation: This is a dirty read. If the uncommitted transaction aborts, the reading transaction has invalid data and might have committed, making it irrecoverable.