Which technique involves implementing a sequence of modifications to the cover to obtain a stego-object?

• A. Distortion Techniques
• B. Substitution Techniques
• C. Cover Generation Techniques
• D. Transform Domain Techniques

Answer: (A)

Distortion techniques embed by applying a carefully chosen series of changes to the cover to carry the secret data, producing the stego-object. Each modification is guided by a distortion measure, aiming to keep the cover visually and statistically close to the original while encoding the payload. This makes the embedding process inherently about sequencing edits across the cover rather than just swapping bits or generating a new object. Substitution would be a more direct, single-step replacement of data with payload bits; cover generation creates the stego object from scratch rather than modifying an existing cover; transform domain techniques insert changes in a transformed (frequency) domain. So the described approach fits distortion techniques best.