I want to know the answer to the following question:
Elimination of what helped the efficiency of diesel traction to go up?
All the background I'm provided with is that "The conversion of wheel bearings from plain to roller, increase of train weight, converting single track lines to double track (or partially double track), and the elimination of obsolete 2-axle freight cars increased the energy-efficiency of all types of traction: electric, diesel, and steam.". Is that enough to answer the question?
Answer: yes