The damaged leg is not regenerated in

The correct option is frog.

Regeneration is the natural ability of an organism to replace or restore damaged or lost body parts, tissues, or organs. The capacity for regeneration varies significantly across different species and developmental stages:

1. Salamanders: These amphibians are famous for their remarkable regenerative abilities. Even as adults, they can fully regenerate complex structures such as complete limbs, tails, jaws, and parts of their heart and eyes.
2. Frog's tadpoles: During their larval (tadpole) stage, frogs possess the ability to regenerate lost limbs and tails. This capacity is highly active during early development.
3. Crabs: As crustaceans, crabs can easily regenerate lost limbs (legs and claws) through successive molting cycles.
4. Adult Frogs: As a frog undergoes metamorphosis from a tadpole to an adult, it loses its capacity to regenerate complex structures like limbs. If an adult frog loses or damages a leg, the wound heals by forming a scar (fibrous tissue) rather than regenerating the lost limb.

Therefore, the damaged leg is not regenerated in an adult frog.