Which of the following represents the correct combination without any exception ?

In Chondrichthyes, mouth is ventral, gills lack operculum, skin has placoid scales, notochord is persistent (Ref. NCERT Textbook)Note: There are exceptions like Chimera which has an operculum covering the gill-slits on each side. Such an exception must be ignored (not covered in the NCERT textbook) while selecting the most appropriate answer. Cyclostomes do not have In birds, skin is dry and without glands, except for the oil gland present at the base of the tail.In mammalia, pinnae are absent in some (e.g., monotremes, whales, dolphins). Two pairs of limbs are not present in all e.g., in whales, forelimbs are modified into flippers and hindlimbs are vesitigial.