Two unknown compounds $X$ and $Y$,both having molecular formula $C_4H_8O$,give the following results with four chemical tests.

Compound	Bromine	$Na$ metal	Chromic acid	Lucas reagent
$X$	decolourises	bubbles	Orange to Green	No reaction
$Y$	No reaction	No reaction	No reaction	No reaction

Compound $X$ and $Y$ respectively are:

• A
  $CH_3-CH_2-CO-CH_3$ and $CH_3-CH_2-CH_2-CHO$
• B
  $CH_2=CH-CH_2-CH_2OH$ and $tetrahydrofuran$
• C
  $tetrahydrofuran$ and $CH_2=CH-CH_2-CH_2OH$
• D
  $CH_3-CH_2-CH_2-CHO$ and $CH_3-CH_2-CO-CH_3$