Based on the initial constraints the line looks like _OR_M_ _. Looking at 23, based on that local condition and the original constraint about "specialty" and the fact that P and S must come at least one before M, is it not the case that P must go immediately to the left of M to make _ORPM_ _?
So why is the correct Must Be True answer that P is at least 1 before S? Wouldn't that at the very least make S in the same slot as M thereby violating the initial constraint about P and S being at least 1 before M?
I'm sure I'm just missing something stupid and it's going to be embarassing, but this has been driving me nuts, I can't see what I'm doing wrong, especially since I got all the other questions right!