Diminishing Marginal Returns Often Arise Because the

Diminishing marginal returns often arise because the

A) additional worker hired is lazier than the existing workers.
B) additional worker hired must share the same machines and workspace.
C) additional worker hired must be trained for a long period of time to use the machines and tools.
D) existing plant size and workplace is much too large.
E) existing plant is technologically behind the industrial average.