We are looking for the answer choice that CANNOT work.
(D) states that V and Z are the complete assignments to L. Rule #4 tells us that Y and Z must both be assigned to P if either is, and since Z is already assigned to a different class, we know that we can't put Y in P. Therefore, we must put it in M. Since there are exactly two spots in M, we must fill the second spot with R. S and T, which must go together, are both assigned to P. This gives us the following valid scenario: L: VZ M: YR P: ST
(B) states that R and Z are the complete assignments to L. As in answer choice (D), we must remember that #4 says Y and Z must both be assigned to P if either is, and since Z is already assigned to a different class, we know that we can't put Y in P. Therefore, we must put it in M. There is exactly one spot left in M (because Rule #1 says M has exactly two assignments), so we cannot put S and T there because Rule #2 says they must go together. Therefore, S and T are assigned to P and the only remaining option to fill the second spot in M is V. This gives us: L: RZ M: YV P: ST However, this is an invalid scenario because it violates Rule #3, which states that V and Y can not be assigned to the same course. Therefore, (B) is the correct answer for a scenario that CANNOT work.
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