In the isochemical phase diagram shown below, the curved arrow represents the P-T path. The variance at peak metamorphism is _. 
In the isochemical phase diagram shown below, the curved arrow represents the P-T path. The variance at peak metamorphism is _. 
In the isochemical phase diagram shown below, the curved arrow represents the P-T path. The variance at peak metamorphism is _.

The units A to H marked on the figure represent different rock formations. Select the option that describes the chronological sequence from old to young.
