Match the organisms given in Column $I$ to their functions given in Column $II$ and choose the correct option.

Column $I$	Column $II$
$A$. Thiobacillus	$1$. Free-living nitrogen-fixing cyanobacteria
$B$. Nitrosomonas	$2$. Denitrification
$C$. Nostoc	$3$. Free-living aerobic nitrogen-fixing bacteria
$D$. Azotobacter	$4$. $NH_{3}$ to Nitrite

Codes:
$A \quad B \quad C \quad D$

• A
  $2 \quad 4 \quad 1 \quad 3$
• B
  $4 \quad 1 \quad 3 \quad 2$
• C
  $2 \quad 4 \quad 1 \quad 3$ (Correction: $A-2, B-4, C-1, D-3$)
• D
  $3 \quad 2 \quad 4 \quad 1$