Biology · ANIMAL KINGDOM

A comparative physiological study is conducted on *Psittacula* (Parrot) and *Pteropus* (Flying fox). Both animals are capable of flight and maintain a constant body temperature. Which of the following options correctly highlights a functional difference in their respiratory systems while reflecting their shared circulatory trait?

1. *Psittacula* possesses a three-chambered heart with air sacs, whereas *Pteropus* possesses a four-chambered heart without air sacs.
2. *Pteropus* utilizes vascularized skin for supplementary respiration, while *Psittacula* relies exclusively on pulmonary air sacs.
3. Both organisms possess lungs supplemented by interconnected air sacs, but *Psittacula* has a four-chambered heart while *Pteropus* has a two-chambered heart.
4. *Psittacula* has air sacs connected to lungs to supplement respiration, whereas *Pteropus* lacks air sacs connected to lungs; both possess a four-chambered heart.