Which of the following can cause DNA damage and mutations in humans ?

Options

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

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks which type of ultraviolet (UV) radiation can cause DNA damage and mutations in humans. The options provided are different combinations of UVA and UVB radiation.

2. **Identifying UV Radiation Types**:
- **UVA**: This type of UV radiation can penetrate deep into the skin but is less effective at causing direct DNA damage compared to UVB.
- **UVB**: This type of UV radiation is known to cause direct DNA damage, particularly through the formation of pyrimidine dimers.

3. **Analyzing the Options**:
- **Option A (Absorption of UVA and UVB)**: While UVA can cause some damage, UVB is more significant for direct DNA damage.
- **Option B (Absorption of UVB)**: This is the most relevant option since UVB is known to induce dimerization of pyrimidines, leading to DNA damage and mutations.
- **Option C (Absorption of UVA)**: This is less relevant because UVA is not primarily responsible for direct DNA damage.
- **Option D (Absorption of UVA and UVC)**: UVC is mostly absorbed by the ozone layer and does not significantly contribute to DNA damage in humans under normal conditions.

4. **Conclusion**: Based on the analysis, the absorption of UVB radiation is the primary cause of DNA damage and mutations in humans. Therefore, the correct answer is **Option B (Absorption of UVB)**.