This is a general must be true question, and it has the potential to seriously bog you down. Trying every answer would take far too long.
Instead, you should ask who is the most restricted variable. I would say it is J, as it has two rules:
- J can’t go fourth
- J must always have G before it
D has J, and says J makes at most two voyages. If that weren’t true, how many voyages would J make? Three. And that would require three G’s. You’d end up with this:
That doesn’t work. We have a J fourth, and also there’s no space for the two M’s.
D is CORRECT.
For thoroughness, I’ve made some diagrams to disprove the other answers. I didn’t do this in timed conditions, because I was sure D had to be true, and I knew why. I’m including these in case you thought any of the other answers also had to be true.
Of course, on review it is good practice to draw these sorts of diagrams yourself. The more diagrams you practice drawing, the faster you’ll get at it.
This diagram shows that A and E don’t have to be true. G isn’t 1st or 2nd, and the cruise visits T three times:
This diagram shows B doesn’t have to be true:
This diagram shows C doesn’t have to be true. In it, the cruise visits G three times:
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