So, this is the question that truly tripped me up. It is my understanding that, if plan 1 is given as a plan that occurred, it can be the only plan that occurred. I based on the fact that "two assignments of apprentices to projects will be made" and on the fact that plan 1 has two reassignments.
Therefore, since plan 1 is stated as occuring in Q24 either L and N will be reassigned first (leaving NMLO matching up with QRST) or M and O will be reassigned first (leaving LONM matching up with QRST). Am I right in the set-up so far?
And if so, could someone explain why C is not the correct answer?
Although, I do acknowledge that the questions asks "must be true" and technically, since the order of plan 1 is unknown answer C does not have to be true. I just don't understand how the right answer is right.