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A complete log record for a write operation includes

Athe transaction's SQL string only
Btxn id, item id, old value, new value
Conly the new value of the item
Dthe lock mode the transaction acquired
Answer & Solution
Correct answer: B. txn id, item id, old value, new value
Standard log records carry the txn id (to know who), item id (to know what), old value (so undo can restore it) and new value (so redo can re-apply it). The SQL string alone could not be reverse-applied on a crash only the new value cannot undo lock mode is concurrency control, not recovery.
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