FINRA Rule 4511 requires member firms to retain records, including electronic communications, in anon- rewriteable, non-erasable format(often referred to as WORM: Write Once, Read Many). This ensures that records cannot be altered or deleted once stored.
* D is correctbecause firms must store records in a tamper-proof format.
* A,B, andCare incorrect because these formats do not guarantee compliance with the tamper-proof requirements set forth by FINRA and the SEC.