Answer : 4. "Birds"
Explanation :

Answer: D) Birds Explanation: Mammals and Birds are Warm-blooded Animals. Warm-blooded animals have body temperatures that usually stay the same Whether it is sunny and hot outside or there is a snowstorm.They are able to regulate their body temperature which changes with temperature of environment.   Warm Blooded Animals :: Apes, Monkeys, Whales, Elephants, Cheetahs, Giraffes, Pets, Felines, Pigs and Humans(all other live birth bearing creatures that nurse their young)..   Cold Blooded Animals :: All Reptiles, Amphibians, Fish as well as Insects (Bugs).