During an autoimmune disorder

Options

A. the immune system has the ability to differentiate between foreign antigens from self - antigens .
B. the immune system loses the ability to differentiate between foreign antigens from self - antigens
C. the immune system attacks self - cells and causes damage to them .
D. Both (B) and (C)

Answer

### Step-by-Step Solution:

1. **Understanding Autoimmune Disorders**:
- Autoimmune disorders occur when the body's immune system mistakenly attacks its own cells. This happens because the immune system loses its ability to distinguish between self (the body’s own cells) and non-self (foreign antigens).

2. **Identifying the Key Concepts**:
- The immune system normally has the ability to differentiate between foreign antigens (like pathogens) and self-antigens (the body’s own cells).
- In autoimmune disorders, this ability is compromised.

3. **Analyzing the Options**:
- **Option A**: "The immune system has the ability to differentiate between foreign antigens from self antigens."
- This is incorrect in the context of autoimmune disorders because, during these disorders, the immune system fails to differentiate.
- **Option B**: "Immune system loses the ability to differentiate between foreign antigens from self antigens."
- This is correct; it describes a key characteristic of autoimmune disorders.
- **Option C**: "Immune system attacks self cells and causes damage to them."
- This is also correct; it describes the consequence of the immune system's failure to differentiate.
- **Option D**: "Both B and C."
- Since both B and C are correct, this option is also correct.

4. **Conclusion**:
- The correct answer is **Option D: Both B and C**. This option accurately reflects the nature of autoimmune disorders.