Onsider the redox reaction below. Upper M g (s) plus Pper f e superscript 2 plus (a q) right arrow upper M g superscript 2 plus (a q) plus upper F e (s). Which equation is a half reaction that describes the reduction that is taking place? Upper F e superscript 2 plus (a q) plus 2 e superscript minus right arrow upper F e (s). Upper M g (s) right arrow upper M g superscript 2 plus (a q) plus 2 e superscript minus. Upper Fe superscript 2 plus (a q) right arrow upper F e (s) plus 2 e superscript minus. Upper M g (s) plus 2 e superscript minus right arrow upper Mg superscript 2 plus (a q).