Make the correct pairs from below mentioned $'X'$ and $'Y':$

$1. \text{Sulphurous acid}$	$p. H_{3}PO_{4}$
$2. \text{Sulphuric acid}$	$q. H_{2}S_{2}O_{7}$
$3. \text{Oleum}$	$r. H_{2}SO_{3}$
$4. \text{Phosphoric acid}$	$s. H_{2}SO_{4}$

• A
  $(1-q), (2-s), (3-r), (4-p)$
• B
  $(1-p), (2-q), (3-r), (4-s)$
• C
  $(1-r), (2-s), (3-q), (4-p)$
• D
  $(1-s), (2-q), (3-r), (4-p)$