Select the correct statement with respect to locomtion in humans `:`

Options

A. The joint between adjacent vertebrae is a fibrous joint
B. A decreased level of progesterone causes osteoporosis in old prople
C. Accumulation of uric acid crystals in joints causes their inflammation
D. The vertebral column has 10 thoracic vertebrae

Answer

To solve the question regarding locomotion in humans, we need to evaluate the provided statements one by one to identify the correct one.

### Step-by-Step Solution:

1. **Evaluate the first statement**:
- The statement claims that the joint between adjacent vertebrae is a fibrous joint.
- This is incorrect because the joints between adjacent vertebrae are actually classified as **synovial joints**, specifically the intervertebral joints, which allow for a range of motion.

2. **Evaluate the second statement**:
- This statement suggests that a decreased level of progesterone causes osteoporosis in old people.
- This is also incorrect. Osteoporosis is primarily associated with a decrease in **estrogen** levels, particularly in postmenopausal women, rather than progesterone.

3. **Evaluate the third statement**:
- The statement mentions that the accumulation of uric acid crystals in joints causes inflammation.
- This is correct. The condition known as **gout** is characterized by the deposition of uric acid crystals in the joints, leading to inflammation, pain, and swelling.

4. **Evaluate the fourth statement**:
- This statement claims that the vertebral column has 10 thoracic vertebrae.
- This is incorrect because the human vertebral column actually contains **12 thoracic vertebrae**.

### Conclusion:
After evaluating all the statements, the correct answer is the third statement regarding the accumulation of uric acid crystals in joints causing inflammation.

### Final Answer:
The correct statement with respect to locomotion in humans is: **The accumulation of uric acid crystals in joints causes their inflammation.**

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