Match the following columns and select the correct option.

	Column I		Column II
(a)	6-15 pairs of gill slits	(i)	Trygon
(b)	Heterocercal caudal fin	(ii)	Cyclostomes
(c)	Air Bladder	(iii)	Chondricthyes
(d)	Poison sting	(iv)	Osteicthyes

	a	b	c	d
1	ii	iii	iv	i
2	iii	iv	i	ii
3	iv	ii	iii	i
4	i	iv	iii	ii

A-II, B-III, C-IV, D-I
A. Cyclostomes possess 6-15 pairs of gillslits.
B. Chondrichthyes possess heterocercal caudal fi n (the dorsal lobe is larger than the ventral lobe).
C. An air bladder regulates buoyancy in the members of Osteichthyes (bony fishes).
D. A poison sting is present on the dorsal side of the tail in Trygon (stingray). It is useful for defence and capture of the prey.