Given the reaction C O2 Upper C plus Upper O subscript 2 right arrow upper C upper O subscript 2. CO2 which pair of reactions represents the two half-reactions? First: upper C right arrow upper C upper O subscript 2 plus 4 e superscript minus. Second: upper O subscript 2 plu 4 upper e superscript minus right arrow upper C upper O subscript 2. First: upper C plus 4 e superscript minus right arrow upper C upper O subscript 2. Second: upper O subscript 2 right arrow Upper C upper O subscript 2 plus 4 e superscript minus. First: upper C right arrow upper C upper O subscript 2 plus 2 e superscript plus. Second: upper O subscript 2 plus 2 e superscript minus right arrow upper C upper O subscript 2. First: upper C plus 2 e superscript minus right arrow Upper C upper subscript 2. Second: upper O subscript 2 right arrow upper C upper O subscript 2 plus 2 e superscript minus.