Elements Y and Z are both found in Period 3. Y is the Period 3 element with the smallest atomic radius. In Period 3, only two elements have a melting point lower than that of Z. Y and Z combine to make compound R. Which compound could R be?
- A$\text{MgCl}_2$
- B$\text{MgS}$
- C$\text{Na}_2\text{S}$
- D$\text{PCl}_3$