Which of the following is designed to guarantee that once data is written it cannot be modified? (Select TWO).

Flash memory supports erase-and-rewrite cycles through its floating-gate transistor architecture, so data stored on flash can be modified and does not meet write-once requirements.

DLT4 (Digital Linear Tape 4) is a rewritable magnetic tape format and does not enforce any write-once protection on the data recorded to it.

CD-R uses an organic dye layer that is permanently and irreversibly altered by a laser during the write process, making it physically impossible to overwrite or erase recorded data. This permanent physical change to the medium is what qualifies CD-R as a write-once technology. Because the alteration cannot be reversed, CD-R is commonly used for archival and compliance storage scenarios.

SDLT (Super Digital Linear Tape) is also a rewritable magnetic tape format and provides no mechanism to prevent overwriting or deletion of stored data.

WORM (Write Once Read Many) is a storage classification explicitly designed to guarantee data immutability after the initial write operation, so once data is committed it cannot be modified, deleted, or overwritten by any software or administrative action. This hard immutability guarantee makes WORM storage a regulatory standard in industries such as finance, healthcare, and legal where tamper-proof retention is mandated. The WORM designation applies to both optical and tape-based media that implement this protection.