The scales of which fish are used for jewellery and novelties?

Correct option is A

Ganoid scales (ganoine layer) of gars are hard, shiny, and durable — historically fashioned into decorative items, buttons, and novelty jewelry.
Material Properties & Uses
Composition: ganoine (enamel-like), dentine and bone layers → creates lustrous, abrasion-resistant surface.
Craft uses: small decorative inlays, buttons, brooches, novelty jewelry; prized for natural sheen.
Historical use: 19th–20th century crafts; some artisanal use persists.
Conservation
Gars are region-specific; any commercial use must consider species protection and local regulations.
Notes on other options
Angel fish, Colisa, Danio have thin cycloid/ctenoid scales unsuitable for durable ornamentation.