Exam Multi-Choice Question

In my Property Law exam, the son was entitled to the fixtures and the
daughter was entitled to the chattels under a will. The two were disputing
the title to a house that was resting on stumps. The question asked "which
of the following is the BEST ARGUMENT FOR THE SON?"

a) [obviously incorrect answer]
b) The house is a fixture, therefore the son is entitled to it.
c) As it was not a "personal effect", the house belongs to the son. If the
daughter wants the house, she should pay the son its value independent of the house
d) Both b and c

I selected b), however d) was the "correct" answer. I believe that c) (thus
d)) is incorrect because it implies that the son is obliged to sell the
house if the daughter wishes to purchase it (obviously no such obligation
exists). The lecturer denies that c) that makes such an implication.

Who is right and why?

Thank you
SJ.