A concave lens may be of the following types:

Options

A. bi-concave or double-concave
B. plano concave
C. convexo-concave
D. all of the above

Explanation

To answer the question "A concave lens may be of the following types:", we will analyze the options provided and identify the types of concave lenses.

### Step-by-Step Solution:

1. **Understanding Concave Lenses**:
- A concave lens is a lens that is thinner at the center than at the edges. It diverges light rays that are incident on it.

2. **Identifying Types of Concave Lenses**:
- There are several types of concave lenses based on their shape:
- **Bi-concave Lens (Double-Concave)**: This type has both surfaces curved inward. It is symmetric and diverges light rays from both sides.
- **Plano-Concave Lens**: This lens has one flat (plano) surface and one concave surface. It diverges light rays from the curved side while the flat side does not affect the light.
- **Convexo-Concave Lens**: This lens has one surface that is convex (bulging outward) and the other surface that is concave. It can also diverge light rays depending on the curvature of the surfaces.

3. **Conclusion**:
- All the mentioned types (bi-concave, plano-concave, and convexo-concave) are valid types of concave lenses. Therefore, the correct answer to the question is "All of the above".

### Final Answer:
- A concave lens may be of the following types: **All of the above** (Bi-concave, Plano-concave, Convexo-concave).

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