Biology · ANIMAL KINGDOM

While evaluating diagnostic mammalian characters, an investigator compares *Ornithorhynchus* (Platypus) with *Macropus* (Kangaroo). Which of the following statements accurately identifies the combination of traits present in *Ornithorhynchus* that distinguishes it from *Macropus*?

1. Absence of mammary glands combined with oviparity, indirect development, and a three-chambered heart.
2. Presence of hair on skin and viviparity combined with internal fertilisation and cold-blooded nature.
3. Presence of mammary glands and milk-producing capability combined with oviparity and absence of external pinnae.
4. Viviparity combined with presence of external ears (pinnae), homoiothermy, and four-chambered heart.