Name the most serious threat to wildlife.

Explanation

**Step-by-Step Solution:**

1. **Identify the Threats to Wildlife:**
- Wildlife faces multiple threats, including over-exploitation of resources, deforestation, human activities, and interference in natural cycles.

2. **Evaluate the Impact of Each Threat:**
- Over-exploitation refers to the excessive use of natural resources, which can lead to the decline of species.
- Deforestation involves cutting down trees, which destroys the natural habitats of many species.
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