Define a food chain. Design a terrestrial food chain of four trophic levels. If a pollutant enters at the producer level, the organisms of which trophic level will have the maximum concentration of the pollutant in their bodies ? What is this phenomenon called ?

Explanation

### Step-by-Step Solution:

1. **Define a Food Chain**:
A food chain is a linear sequence that represents the transfer of energy and nutrients from one trophic level to another in an ecosystem. It shows how different organisms are connected based on their feeding relationships.

2. **Design a Terrestrial Food Chain of Four Trophic Levels**:
- **Trophic Level 1 (Producers)**: Grass (autotrophs that produce their own food through photosynthesis)
- **Trophic Level 2 (Primary Consumers)**: Grasshopper (herbivores that eat grass)
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