Homocercal and heterocercal are forms of:

Correct option is B

Correct Answer: (b) Caudal fin
Explanation:
→ Homocercal and heterocercal describe structural types of caudal (tail) fins in fishes.
→ Homocercal tails appear externally symmetrical, common in teleosts.
→ Heterocercal tails have an asymmetrical structure with the vertebral column extending into the upper lobe (e.g., sharks).
Information Booster:
→ Tail type is linked to swimming style and evolutionary lineage.
→ Homocercal tails provide rapid acceleration and maneuverability.
→ Heterocercal tails generate lift for buoyancy compensation.
Additional Information (Other Options):
(a) Anal, (c) Dorsal, (d) Pelvic fins do not show homocercy/heterocercy classification.