A block of ice is taken out of a freezer. Part of the ice melts and forms water. Some of this water then evaporates. The initial mass of the ice is $p$. The mass of the ice that remains unmelted is $q$. The mass of the water is $r$. The mass of the water vapour is $s$. Which equation shows the relationship between $p$, $q$, $r$ and $s$?
- A$p = q + r$
- B$p = q + r + s$
- C$p = q + r - s$
- D$p = q + s$