 Solution

Scala trait linearization merges parent linearizations from right to left, deleting an earlier occurrence when that same ancestor occurs in a later appended parent linearization. Each class precedes its ancestors, and an ancestor appears once.^[ref] Ignoring the predefined roots gives

Each override appends its letter after super.m returns. Reading the method chain in reverse from K therefore yields the three output lines:

KIGJFDA
KIGJFDHEB
KJHEC

In particular, mixing H into C again does not create another H or move it before its subclass E. Also, J lies between F and G in D's chain; super follows the final linearization, not simply one statically named parent.