A combination of two Period 3 oxides is placed in water. A solution is produced and its pH is slightly below $7$. Which oxides might be present in the mixture?
- A$\text{Al}_2\text{O}_3$ and $\text{MgO}$
- B$\text{Na}_2\text{O}$ and $\text{MgO}$
- C$\text{Na}_2\text{O}$ and $\text{P}_4\text{O}_{10}$
- D$\text{SO}_3$ and $\text{P}_4\text{O}_{10}$