R is a water solution of an ionic compound. When R is mixed with $\mathrm{Sr(NO_3)_2(aq)}$, a white precipitate appears. If R is mixed with dilute $\mathrm{HNO_3(aq)}$, no visible change occurs. What anion is present in compound R?
- A$\mathrm{Cl^-}$
- B$\mathrm{SO_4^{2-}}$
- C$\mathrm{HCO_3^-}$
- D$\mathrm{CO_3^{2-}}$