Which one of the following is not a true amphibian animal

Options

A. salamander
B. toad
C. tortoise
D. frog

Answer

To determine which of the following animals is not a true amphibian, we will analyze each option provided:

1. **Salamander**: Salamanders are indeed classified as amphibians. They possess features typical of this class, such as a moist skin and the presence of a tympanum, which is an auditory structure.

2. **Toad**: Toads are also true amphibians. They share similar characteristics with frogs and salamanders, including the absence of a pinna and the presence of a tympanum.

3. **Tortoise**: Tortoises are not amphibians; they are reptiles. Unlike amphibians, tortoises have a hard shell and possess a pinna, which is characteristic of reptiles.

4. **Frog**: Frogs are classic examples of amphibians. They have moist skin, undergo metamorphosis, and possess a tympanum.

Based on this analysis, the animal that is not a true amphibian is the **tortoise**.

### Final Answer:
The correct answer is **Tortoise** (Option 3).