Which of the following is an age-related bone disorder characterized by decreased bone mass and increased chances of fracture ?

Options

A. Osteoarthritis
B. Osteoporosis
C. Muscular dystrophy
D. Myasthenia gravis

Answer

To solve the question regarding the age-related bone disorder characterized by decreased bone mass and increased chances of fracture, we will analyze the options provided.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for an age-related bone disorder that leads to decreased bone mass and an increased risk of fractures. This indicates that we are looking for a specific condition that affects the bones as people age.

2. **Analyzing the Options**:
- **Option A: Osteoarcheteris**: This condition involves damage to flexible tissue in the bones, but it is not primarily characterized by decreased bone mass or age-related factors. Therefore, this option is incorrect.

- **Option B: Osteoporosis**: This is a well-known age-related bone disorder that is characterized by decreased bone mass and an increased risk of fractures. It primarily affects older adults, especially postmenopausal women. This option fits the description given in the question.

- **Option C: Muscular Dystrophy**: This is a genetic condition that leads to the loss of muscle mass and strength, not specifically related to bone mass or fractures. Thus, this option is also incorrect.

- **Option D: Myasthenia Gravis**: This is an autoimmune disorder that leads to rapid fatigue of muscles, but it does not relate to bone mass or fractures. Therefore, this option is incorrect as well.

3. **Conclusion**: Based on the analysis of the options, the correct answer is **Option B: Osteoporosis**. This condition is specifically characterized by decreased bone mass and increased chances of fractures, particularly in older individuals.

### Final Answer:
**Osteoporosis (Option B)** is the age-related bone disorder characterized by decreased bone mass and increased chances of fracture.