Name the most productive and most diverse part of coastal region.

Explanation

**Step-by-Step Solution:**

1. **Identify the Coastal Region**: The coastal region is the area where land meets the sea. It includes various ecosystems that support a wide range of life forms.

2. **Define Productivity**: In ecological terms, productivity refers to the rate at which energy is produced and stored by organisms, particularly through photosynthesis in plants.

3. **Define Diversity**: Diversity in an ecosystem refers to the variety of species present, including plants, animals, and microorganisms, as well as the genetic diversity within those species.

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