Hi, we have our initial setup in which we know that L and M teach the same language, and since that language cannot be f or r, it must be g.
J _ L/M_ S _ L/M_ F g r
For this question we know that p is at the junior school and doesn't teach French, so P must teach R. This also enables us to place N at the senior school.
J _ L/M P S _ L/M N F g r
This is why D must be true.
To get to this point, you should aim to make deductions that help you place items, and when given a question that sets up a scenario like this, figure out what other parts of that scenario can be determined.
