Which of the following refers to oxidation reaction $(0),$ and which refers to reduction reaction $(R)?$

Further, in each equation circle the oxidized form and box the reduced form.

gain of electrons

$FAD{H}_2$FAD$+2H^{+}+2e^{-}$

$2N^{-}$

NADH$+H^{+}NA{D}^{+}+2H^{+}+2e^{-}$

$NAD{P}^{+}+2H^{+}+2e^{-}$NADPH$+H^{+}$

loss of electrons

FAD$+2H^{+}+2e^{-}FAD{H}_2$

releases energy

NADPH$+H^{+}NAD{P}^{+}+2H^{+}+2e^{-}$

$F{e}^{+3}F{e}^{+2}$

absorbs energy