Which rays are harmful for us?

Explanation

**Step-by-Step Solution:**

1. **Identify the Rays:** The question asks which rays are harmful to us. The primary type of rays that are harmful are ultraviolet rays, commonly known as UV rays.

2. **Understand the Source:** UV rays primarily come from the sun. They are part of the electromagnetic spectrum and are not visible to the human eye.

3. **Recognize the Protective Layer:** The Earth has a protective layer called the ozone layer. This layer absorbs most of the UV radiation from the sun, preventing it from reaching the Earth's surface and causing harm.

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