Which of the following set of characters are present in all mammals without exception?
All mammals are characterised by a muscular diaphragm and milk producing glands, without any exception.
Testes are abdominal in prototherians (e.g., platypus), and some eutherians such as elephants, rihinoceros, whales, dolphins and sea cows.
Platypus is oviparous.
A few mammals such as porpoises and armadillos have homodont teeth.