In which of the following places malaria can be seen commonly?
A. Deserts
B. Wet and worm weather
C. Cold and dry region
D. Wet and humid region

Options

A. A and B
B. C and D
C. B and D
D. A and C

Answer

To determine where malaria is commonly found, we need to analyze the provided options based on the environmental conditions conducive to the transmission of malaria.

### Step-by-Step Solution:

1. **Understanding Malaria Transmission**: Malaria is transmitted by the Anopheles mosquito, which thrives in warm, humid environments. The presence of standing water is crucial for mosquito breeding.

2. **Analyzing Option A: Deserts**: Deserts are characterized by dry conditions with very little moisture. This environment is not suitable for the breeding of mosquitoes. Therefore, malaria is not commonly found in deserts.

3. **Analyzing Option B: Wet and Warm Weather**: Wet and warm weather provides favorable conditions for mosquito breeding. The combination of moisture and warmth can support the life cycle of the malaria-causing parasite, Plasmodium. Thus, malaria can be commonly seen in this type of environment.

4. **Analyzing Option C: Cold and Dry Region**: Cold and dry regions are not conducive to mosquito survival or breeding. The low temperatures and lack of moisture make it unlikely for malaria to be present in these areas.

5. **Analyzing Option D: Wet and Humid Region**: Similar to wet and warm weather, wet and humid regions also provide ideal conditions for the breeding of mosquitoes. This environment is highly conducive to the transmission of malaria.

6. **Conclusion**: Based on the analysis, malaria can be commonly seen in both wet and warm weather (Option B) and wet and humid regions (Option D). Therefore, the correct options are B and D.

### Final Answer:
Malaria can be commonly seen in:
- B. Wet and warm weather
- D. Wet and humid region