Question

Which of the following characteristic features always holds true for the corresponding group of animals?

• A. Cartilaginous endoskeleton - Chondrichthyes
• B. Viviparous - Mammalia
• C. Possess a mouth with an upper and a lower jaw - Chordata
• D. 3 - chambered heart with one incompletely divided ventricle - Reptilia

Answer 1

The correct option is A Cartilaginous endoskeleton - Chondrichthyes

Chondrichthyes are the class of vertebrate animals characterized by the presence of cartilaginous endoskeleton.
All mammals are viviparous except platypus and the echidnas.
Not all Chordates have jaw. Chordates can be gnathostomata (with jaw) and agnatha (without jaws).
Reptillia has an order crocodilian which shows 4 chambered heart