Choose the correct statement.

Cyclostomata (e.g., lamprey and hagfish) is included under Agnatha (jawless vertebrates). They lack jaws and paired fins. 
(1) Not all mammals are viviparous. Prototherians (e.g., platypus) are oviparous (egg-laying).
(3) The heart is not three-chambered in all reptiles. Crocodiles have a fourchambered heart.
(4) Gills are covered by an operculum only in Osteichthyes. In Chondrichthyes, the gill-slits are naked, not covered by an operculum.