I think the D students are the ones with the most challenges. They are good enough to attend college but not for significant merit based scholarships. Their parents can’t afford to pay so they either go local if possible, go into significant debt or don’t go to college (or worse some combination of the above). Both of my kids could easily have been Ds if they had been B students. As it was I had one B and one A. It’s worked out very well thusfar.