Which chemical process is the most sustainable in terms of the atom economy of the copper produced?
CuO+CO→Cu+CO2\text{CuO} + \text{CO} \rightarrow \text{Cu} + \text{CO}_2CuO+CO→Cu+CO2
CuO+H2→Cu+H2O\text{CuO} + \text{H}_2 \rightarrow \text{Cu} + \text{H}_2\text{O}CuO+H2→Cu+H2O
2CuO→2Cu+O22\text{CuO} \rightarrow 2\text{Cu} + \text{O}_22CuO→2Cu+O2
2CuO+C→2Cu+CO22\text{CuO} + \text{C} \rightarrow 2\text{Cu} + \text{CO}_22CuO+C→2Cu+CO2