Black-foot disease is caused by ground water contaminated with:

Options

A. Nitrate
B. Fluoride
C. Arsenic
D. Sulphur

Answer

**Step-by-Step Solution:**

1. **Identify the Question:** The question asks about the cause of Black-foot disease, specifically what contaminant in groundwater is responsible for it.

2. **Review the Options:** The options provided are:
- Nitrate
- Fluoride
- Arsenic
- Sulfur

3. **Evaluate Each Option:**
- **Nitrate:** Excess nitrate in drinking water can lead to health issues like blue baby syndrome, which is not related to Black-foot disease.
- **Fluoride:** While excess fluoride can lead to dental and skeletal issues (fluorosis), it is not linked to Black-foot disease.
- **Arsenic:** High levels of arsenic in groundwater are known to cause arsenic poisoning, which is directly associated with Black-foot disease. This disease is characterized by peripheral vascular issues and can lead to severe health complications.
- **Sulfur:** Excess sulfur in groundwater may cause gastrointestinal issues such as diarrhea and dehydration, but it is not related to Black-foot disease.

4. **Conclusion:** After evaluating all the options, arsenic is the contaminant that causes Black-foot disease. The World Health Organization (WHO) has set a safe limit for arsenic in drinking water at 0.01 milligrams per liter.

5. **Final Answer:** The correct answer is **Arsenic** (Option 3).

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