UPSC 2015 CDS I GK Paper

Among the given items,statement 3 is not true for mammals. It is because heart in mammals is four-chambered.General characteristics of mammals are:
1. Mammals are endothermic vertebrates;
2. Mammals have hair and fur on the body;
3. Mammals have mammary glands;
4. Mammals have four-chambered hearts;
5. Mammals possess one single jaw bone;
6. Mammals have three small bones in the middle of the ear.