In frog which are the typical vertebrae, numbering ……………

Options

A. 1st
B. 2nd to 7th
C. 8th and 9th
D. All of these

Answer

### Step-by-Step Solution

1. **Understanding the Question**: The question asks about the typical vertebrae in frogs and their numbering.

2. **Identifying the Classification**: Frogs belong to the phylum Chordata and class Amphibia. They are classified as tailless amphibians.

3. **Defining Vertebrae**: Vertebrae are the individual bones that make up the spine or vertebral column. They are part of the skeletal system and serve to protect the spinal cord.

4. **Counting the Vertebrae in Frogs**: Frogs have a total of nine vertebrae, which are referred to as signet ring vertebrae, along with one long rod-like structure called the urostyle.

5. **Identifying the First Vertebra**: The first vertebra in frogs is the cervical vertebra, known as the atlas, which articulates with the skull.

6. **Identifying Typical Vertebrae**: The second to seventh vertebrae are considered the typical vertebrae in frogs. They are characterized by a proselytis condition, meaning the anterior side is concave and the posterior side is convex.

7. **Identifying Other Vertebrae**: The eighth vertebra is in an ampicellar condition (concave on both sides), and the ninth vertebra is the sacral vertebra, which is biconvex (convex on both sides).

8. **Conclusion**: Based on the above information, the typical vertebrae in frogs are the second to seventh vertebrae.

### Final Answer
The typical vertebrae in frogs are numbered from the **2nd to the 7th vertebra**.

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