When substance $A$ reacts with water,it produces a combustible gas $B$ and a solution of substance $C$ in water. When another substance $D$ reacts with solution $C$,it produces the same gas $B$,even when reacting with dilute sulfuric acid at room temperature. $A$ gives a golden yellow flame in a Bunsen burner flame. What are $A, B, C,$ and $D$ respectively?

• A
  $Na, H_2, NaOH$ and $Zn$
• B
  $K, H_2, KOH$ and $Al$
• C
  $Ca, H_2, Ca(OH)_2$ and $Sn$
• D
  $CaC_2, C_2H_2, Ca(OH)_2$ and $Fe$