To solve this problem, we need to identify who coined the term "ecosystem." Let's analyze the options:$\newline \bullet$Option 1: E.P. Odum - E.P. Odum is known for his work in ecology and for popularizing the concept of ecosystems, but he did not coin the term.$\newline \bullet$Option 2: A.G. Tansley - A.G. Tansley was a British ecologist who introduced the term "ecosystem" in 1935.$\newline \bullet$Option 3: E. Haeckel - E. Haeckel was a German biologist who coined the term "ecology," not "ecosystem."$\newline \bullet$Option 4: E. Warming - E. Warming was a Danish botanist known for his contributions to plant ecology, but he did not coin the term "ecosystem."$\newline$Based on this analysis, the correct answer is Option 2: A.G. Tansley.$\newline$Therefore, the correct option is Option 2.