Based on the following passage, which of the following would be an example of a sustainable input for the construction industry? Advocates for sustainable construction acknowledge that the planet’s built environment is the largest single contributor to pollution and ecosystem destruction in the world—larger even than the pollution caused by the internal combustion engine. The built environment relies on inputs of land, water use, raw materials, and energy. Its outputs include water pollution, solid waste, and carbon emissions.

A. hemp and straw

B. cold-formed steel

C. gray water

D. old-growth wood