Viruses ate .................. obligate parasites.

Explanation

**Step-by-Step Solution:**

1. **Understanding Parasites**:
- Parasites are organisms that depend on other living organisms (hosts) for their survival, nourishment, and reproduction. They often harm the host in the process.

2. **Characteristics of Viruses**:
- Viruses are unique in that they cannot carry out metabolic processes on their own. They are considered inert (inactive) when outside a living host.

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