Which of these has the least number of movable joints?

Options

A. Skull
B. Backbone
C. Arms and hands
D. Legs and feet

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which of the given options has the least number of movable joints. We need to analyze each option to determine the number of movable joints present.

2. **Analyzing the Options**:
- **Option 1: Skull**: The skull primarily consists of immovable joints. About 95% of the joints in the skull are immovable, with only 5% being movable (like the lower jaw).
- **Option 2: Backbone**: The backbone is made up of vertebrae, which are small bones that allow for flexibility and movement. Therefore, the backbone has a significant number of movable joints.
- **Option 3: Arms and Hands**: The arms and hands contain various types of joints (hinge, gliding, ball and socket) that allow for a wide range of movements. This means they have a high number of movable joints.
- **Option 4: Legs and Feet**: Similar to the arms and hands, the legs and feet also have many joints that facilitate movement, indicating a high number of movable joints.

3. **Comparing the Options**:
- The skull has the least number of movable joints (only 5%).
- The backbone, arms, and legs all have a greater number of movable joints compared to the skull.

4. **Conclusion**: Based on the analysis, the option with the least number of movable joints is the **Skull**.

**Final Answer**: The skull has the least number of movable joints.

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