Which statement is an approach to industrial ecology? 

A)  maximize the input of energy per unit of output 
B)  adjust inputs and outputs to the carrying capacity of the environment 
C)  maximize the input of matter resources per unit of output 
D)  make resource use an open system

Approach B – adjusting inputs and outputs to the carrying capacity of the environment – is a key principle of industrial ecology which aims to promote sustainable and efficient use of resources while minimizing waste and environmental damage. Approach A – maximizing input of energy per unit of output – is not a sustainable approach as it does not factor in the finite nature of resources and can lead to overuse and depletion. Approach C – maximizing input of matter resources per unit of output – can similarly lead to the unsustainable use of resources. Approach D – making resource use an open system – is not a clear or specific approach to industrial ecology and does not address the need for resource efficiency and waste reduction.