The correct option is A Lizard
Reptiles have exoskeleton made of dry skin and scales. They lay eggs outside water and generally have a three chambered heart.
Example: Lizard, snake, crocodile.
Crocodile is the only reptile with a four chambered heart.
Frog comes under class Amphibia and possess a three chambered heart.
Fish comes under class Pisces and possess a two chambered heart.