Which Description Does Not Fit the Definition of an Ecosystem

Multiple Choice

Which description does not fit the definition of an ecosystem study?

A) The transformation of energy through a group of forest-floor species
B) The cycling of carbon through a group of soil bacteria on the forest floor
C) Measurement of primary production by all producers in a large forest
D) Atmospheric nitrogen fixation by plants in a forest environment
E) Competitive and cooperative interactions among forest-floor beetle species