The correct answer is option 2, which states that Amphibia and Reptilia are the classes of animals that have a three-chambered heart.

To better understand this, let`s dissect each option:

Option 1: Pisces and Amphibia. This option suggests that both Pisces (fish) and Amphibia (amphibians) have a three-chambered heart. However, this is not accurate as fishes actually have a two-chambered heart.

Option 2: Amphibia and Reptilia. This is the correct answer. Amphibia includes animals like frogs, toads, and salamanders, and they indeed have a three-chambered heart. Similarly, Reptilia, which includes reptiles such as snakes, turtles, and crocodiles, also have a three-chambered heart.

Option 3: Reptilia only. This option states that only reptiles have a three-chambered heart. However, as we discussed earlier, amphibians also fall under this category.

Option 4: Amphibia only. This option suggests that only amphibians have a three-chambered heart. While it is true that amphibians have a three-chambered heart, reptiles also share this characteristic.

Therefore, option