Which of the following part of body is having a single bone in mammals?

Options

A. pelvic girdle
B. Upper jaw
C. Wrist
D. Lower jaw

Answer

To determine which part of the body has a single bone in mammals, we will analyze each option provided.

1. **Pelvic Girdle**:
- The pelvic girdle is made up of two hip bones (the ilium, ischium, and pubis). Therefore, this option is incorrect.

2. **Upper Jaw (Maxilla)**:
- The upper jaw, also known as the maxilla, consists of two bones. Thus, this option is also incorrect.

3. **Wrist**:
- The wrist is composed of eight small bones known as carpals. Hence, this option is incorrect as well.

4. **Lower Jaw (Mandible)**:
- The lower jaw, or mandible, is the only bone in the lower part of the jaw and is movable. This is the correct answer as it is the only part of the body with a single bone in mammals.

**Final Answer**: The part of the body that has a single bone in mammals is the **Lower Jaw (Mandible)**.

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