A

The projecting “wings” of a winged clamp tend to overlie the crown/root on periapical films, so they can obscure the apex and make accurate working-length radiographs difficult; therefore good radiographic visualization of the full canal length is not an advantage of the winged retainer, whereas the other three features are true benefits (added stability, extra bucco-lingual soft-tissue retraction, and the ability to place dam, clamp and frame together) [Doshi et al., J Conserv Dent, PMID 37205893].