A concave lens is a converging lens.

Explanation

**Step-by-Step Solution:**

1. **Understanding Lens Types**:
- Lenses are categorized into two main types: converging (convex) lenses and diverging (concave) lenses.
- A converging lens focuses parallel rays of light to a point, while a diverging lens spreads out parallel rays.

2. **Identifying the Lens in Question**:
- The question states "A concave lens is a converging lens."
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