Step 1: Question comprehension: Identify the intaglio technique utilizing rosin dust for an acid-resistant ground, yielding tonal variations, not sharp lines.
Step 2: Option assessment.
Lino cut is a relief method, acid is not involved.
Aquatint is an intaglio technique. Rosin powder is applied to a metal plate, then heated, creating a porous ground. Acid etches the plate between rosin particles, generating a textured, tonal surface for ink retention. This matches the criteria.
Drypoint is intaglio; the image is directly incised onto the plate. Acid is not used.
Mezzotint is an intaglio process. A rocker roughens the plate, forming a dark ground; the image is then created by smoothing/polishing areas. Acid is not used.