Which one of the following UV radiations is/are moderately harmful to many organisms?

Options

A. UV-A
B. UV-B
C. UV-C
D. UV-A and B

Answer

To determine which UV radiation is moderately harmful to many organisms, we need to analyze the different types of UV radiation and their effects:

### Step 1: Identify the Types of UV Radiation
There are three main types of UV radiation:
- **UVA**: Wavelengths range from 315 to 400 nm.
- **UVB**: Wavelengths range from 280 to 315 nm.
- **UVC**: Wavelengths range from 100 to 280 nm.

### Step 2: Assess the Harmfulness of Each Type
- **UVA**: This type has the longest wavelength and is considered the least harmful. It penetrates the skin more deeply but is less effective at causing direct DNA damage.
- **UVB**: This type has a shorter wavelength than UVA and is more harmful. It can cause sunburn and has a significant role in the development of skin cancer.
- **UVC**: This type has the shortest wavelength and is the most harmful. It is mostly absorbed by the ozone layer and does not reach the Earth's surface in significant amounts.

### Step 3: Determine the Moderately Harmful Radiation
Given the information about the harmfulness of each type:
- **UVA** is the least harmful.
- **UVB** is moderately harmful.
- **UVC** is the most harmful.

Thus, **UVB** is the type of UV radiation that is moderately harmful to many organisms.

### Conclusion
The answer to the question is **UVB**.

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