The graph illustrates how pH affects the activity of three separate enzymes. The table gives the pH values of different sections of the alimentary canal: mouth pH $7.0$, stomach pH $2.0$, small intestine pH $8.5$. Which enzymes shown in the graph are most likely to be protease enzymes?
- AX, Y and Z
- BX and Z only
- CY and Z only
- DZ only