The correct option is A Tansley
A. Arthur George Tansley coined the term ecosystem' in 1935 to describe the interactions between organisms and with their environment.
B. Odum was an American biologist who worked on ecosystem ecology and wrote the book 'Fundamentals of ecology'.
C. Eugenius warming was the first to write a textbook on plant ecology. He gave the concept and content on ecology.
D. Darwin gave a theory of natural selection which states that only fittest individuals are selected by nature and unfit ones are eliminated.
So, the correct answer is 'Tansley'.