Which of the following type of scales are found in sharks?

Correct option is A

Correct Answer: (a) Placoid
Explanation:
→ Sharks possess placoid scales (denticles) made of enamel-like dentine.
→ These scales reduce drag, increase swimming efficiency, and protect the body.
→ Structurally similar to vertebrate teeth.
Information Booster:
→ Denticles create microturbulence, enabling silent, energy-efficient swimming.
→ Placoid scales are unique to cartilaginous fishes.
→ Also used in hydrodynamic design research.
Additional Information (Other Options):
(b), (c), (d) – found in various bony fishes.