What is the effect of ADH on blood vessels?

Explanation

### Step-by-Step Solution:

1. **Understanding ADH**:
- ADH stands for Anti-Diuretic Hormone, which is produced in the hypothalamus and released by the posterior pituitary gland. Its primary role is to regulate water balance in the body.

**Hint**: Remember that ADH is related to water retention and urine concentration.

2. **Effect on Blood Vessels**:
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