Originally Posted by
mahasamatman
I believe the answers are Y-Z and B-D.
mahatsaman, GoingAway, and bmvaughn are correct.
My IAD-LAX-PHL on one e500 was actually:
A-B-C-D-E with just B-C-D (IAD-LAX-PHL) upgraded. My upgrade was charged at just the B->D distance (IAD-PHL).