Complete the following neutralization reactions: mg(oh)2 + hno3 --> hcl + naoh -->

In neutralisation reactions, acid and base reacts. Acid dissociates to give out H⁺ ions and bases dissociate to give out OH⁻ ions. These H⁺ ions and OH⁻ ions react to form H₂O molecules. 
and the anion from the acid dissociation and cation from base dissociation form salts. 
therefore in a neutralisation reaction acid reacts with base to form water and the corresponding salt
Mg(OH)₂ + 2HNO₃ ---> Mg(NO₃)₂ + 2H₂O
HCl + NaOH ---> NaCl + H₂O

The answer is a) carbon-12