______ is a common passage for both digestive and respiratory systems.

Explanation

**Step-by-Step Solution:**

1. **Identify the Systems Involved**: The question asks for a common passage that is part of both the digestive and respiratory systems. The two systems we need to consider are the digestive system (which processes food) and the respiratory system (which involves breathing).

2. **Understand the Function of Each System**:
- The digestive system is responsible for breaking down food and absorbing nutrients.
- The respiratory system is responsible for taking in oxygen and expelling carbon dioxide.

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