The text stimulus gives values for one product unit. Extraction uses 18 kg CO2e and 40 liters of water; component production uses 42 kg CO2e and 25 liters; assembly uses 10 kg CO2e and 15 liters; transport uses 16 kg CO2e and 5 liters; consumer use uses 34 kg CO2e and 10 liters. If the immediate goal is to reduce the largest listed source of greenhouse-gas emissions, which stage should be investigated first?