We refer to the following as the food chain

Options

A. Large number of human beings forming a human chain near a source of food
B. Large number of animals near a source of food
C. Transfer of food energy from the green plants through a series consumed by organisms
D. None of these

Answer

### Step-by-Step Solution:

1. **Understanding the Concept of Food Chain**:
- A food chain is a sequence that shows how energy and nutrients flow from one organism to another. It typically starts with producers (like plants) and moves through various levels of consumers (herbivores and carnivores).

2. **Analyzing the Options**:
- The question provides four statements, and we need to identify which of these correctly describes a food chain.

3. **Evaluating Each Statement**:
- **Option 1**: "The last number of human beings formed a human chain near the source of food."
- This statement does not describe a food chain. A food chain involves various organisms and their feeding relationships, not just humans forming a chain.

- **Option 2**: "A large number of animals near a food source."
- This statement also does not describe a food chain. While animals may gather around food sources, this does not illustrate the feeding relationships or energy transfer that characterize a food chain.

- **Option 3**: "Transfer of food energy from the green plants through a series consumed by organisms."
- This statement accurately describes a food chain. It highlights the flow of energy from producers (green plants) to various consumers, which is the essence of a food chain.

- **Option 4**: "None of the above."
- Since we have identified a correct statement in Option 3, this option is not applicable.

4. **Conclusion**:
- The only statement that correctly refers to a food chain is Option 3: "Transfer of food energy from the green plants through a series consumed by organisms."

### Final Answer:
The statement that refers to a food chain is: **"Transfer of food energy from the green plants through a series consumed by organisms."**

---