Deficiency of _________ causes a disease known as beri-beri.

Explanation

**Step-by-Step Solution:**

1. **Identify the Disease**: The question asks about a disease known as beriberi.

2. **Research the Cause**: To find out what causes beriberi, we need to look into nutritional deficiencies.

3. **Link to Nutritional Deficiencies**: Beriberi is specifically linked to a deficiency in certain vitamins.

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