Which fertiliser has the greatest percentage by mass of nitrogen? $[M_r:\ \text{NH}_4\text{NO}_3, 80;\ (\text{NH}_4)_3\text{PO}_4, 149;\ (\text{NH}_4)_2\text{SO}_4, 132;\ (\text{NH}_2)_2\text{CO}, 60]$
- A$\text{NH}_4\text{NO}_3$
- B$(\text{NH}_4)_3\text{PO}_4$
- C$(\text{NH}_4)_2\text{SO}_4$
- D$(\text{NH}_2)_2\text{CO}$