Choose the correct answer :
The term ecosystem was coined by :

Options

A. Odum
B. Ernst Haeckel
C. Tansley
D. Reiter

Answer

To answer the question "The term ecosystem was coined by:", we need to analyze the options provided and identify the correct one based on historical context.

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks who coined the term "ecosystem". This requires knowledge of ecological terminology and its origins.

2. **Reviewing the Options**:
- Option A: Odum
- Option B: Haeckel
- Option C: Tansley
- Option D: Ryder

3. **Analyzing Each Option**:
- **Odum**: While E.P. Odum is a significant figure in ecology and known as the father of ecology, he did not coin the term "ecosystem".
- **Haeckel**: Ernst Haeckel was a biologist who contributed to many fields, but he is not credited with coining the term "ecosystem".
- **Tansley**: Arthur Tansley is the ecologist who actually coined the term "ecosystem" in 1935. He defined it to describe the interactions between organisms and their environment.
- **Ryder**: There is no significant contribution to the term "ecosystem" attributed to Ryder.

4. **Identifying the Correct Answer**: Based on the analysis, the correct answer is **C: Tansley**.

### Final Answer:
The term ecosystem was coined by **C: Tansley**.