Three equations are given below. $x$, $y$ and $z$ are all whole numbers. 1. $x\mathrm{Al} + y\mathrm{O_2} \rightarrow z\mathrm{Al_2O_3}$ 2. $x\mathrm{Mg} + y\mathrm{O_2} \rightarrow z\mathrm{MgO}$ 3. $x\mathrm{Na} + y\mathrm{O_2} \rightarrow z\mathrm{Na_2O}$ For which equations is it possible to balance them when $x=4$ and $z=2$?
- A1 and 3
- B1 only
- C2 only
- D3 only