During a redox reaction, the term reduction refers to the gain of electrons. the loss of electrons. the gain of protons. the loss of protons.

Redox  reaction  involve  both  reduction  and  oxidation. Reduction  refers  to  the  gain    of  electrons. Also  it  is refered  to   the decrease  in  oxidation  state  by  molecules  ions  or atom. An  example  of reduction  reaction during combustion  of  wood  where  oxygen  is  reduced   or  gain  electrons  from  carbon.

C. which metal is less dense