When ammonium cyanate is heated without air present, urea, $\text{CO(NH}_2)_2$, is the only substance produced by the reaction. No other products are made. What is the formula of the cyanate ion in ammonium cyanate?
- A$\text{CON}_2^-$
- B$\text{CON}_2^{2-}$
- C$\text{OCN}^-$
- D$\text{OCN}^{2-}$