Question

All mammals without any exception are characterised by

• A. Viviparity and biconcave red blood cells
• B. Extra-abdominal testes and a four-chambered heart
• C. Heterodont teeth and 12 pairs of cranial nerves
• D. A muscular diaphragm and milk producing glands

Answer 1

The correct option is D A muscular diaphragm and milk producing glands

Mammals vary in terms of the pattern of development of their young, the shape of their red blood cells, the structure and formation of their testes, their dentition, and their heart, etc. However, the presence of a muscular diaphragm and mammary glands remain the two constant features observes throughout this class.

So, the correct answer is 'A muscular diaphragm and milk producing glands''.