The correct answer is option 3 - Reptiles. Reptiles include animals such as turtles, snakes, and lizards. They have a diverse range of species that inhabit various habitats around the world. Reptiles are known for their ability to adapt to different environments, which has likely contributed to their large population. They can be found in deserts, forests, grasslands, and even in some freshwater and marine habitats. While fishes and birds also have a significant population, reptiles have the maximum population on the earth. It is important to note that the population of each species within the reptile category can vary, with some species being more common than others.