The answer is D. Mongoose.
A tortoise, frog, rat, and snake are all reptiles. A mongoose is a mammal.
Reptiles are a class of vertebrate animals characterized by dry, scaly skin. They are ectotherms, meaning that their body temperature varies with the environment. Reptiles include snakes, lizards, turtles, tortoises, crocodiles, and alligators.
Mammals are a class of vertebrate animals characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three middle ear bones. These animals are warm-blooded, meaning that their body temperature is regulated internally. Mammals include humans, dogs, cats, cows, pigs, horses, whales, dolphins, and bats.
The mongoose is a small, slender mammal that is native to Africa, Asia, and Europe. It is a carnivore and its diet consists of insects, reptiles, rodents, and small birds. The mongoose is a skilled hunter and is known for its ability to kill snakes.