Which stage of LCA involves inventory of inputs and outputs?

• A. Goal/Scope
• B. Inventory
• C. Impact Assessment
• D. Interpretation

Answer: (B)

In LCA, the stage that collects all data on inputs and outputs is the Inventory phase. This step gathers quantitative information about material and energy flows into and out of the product system across its life cycle—raw materials, energy use, emissions to air, water, and soil, and wastes generated. The inventory creates the dataset of what enters and leaves the system, which is then used to assess environmental impacts in a later stage. The Goal/Scope stage sets purpose and boundaries, the Impact Assessment stage translates the inventory into potential environmental impacts, and Interpretation reviews results and suggests improvements. Because it focuses specifically on compiling the flows of materials, energy, and emissions, the Inventory phase is the correct one.