Sorry to bump this post up again, but I had one last Q:
D is incorrect because of 'previous possibility' which is unidiomatic and should rather be 'possibility previously'?
however, in the latter, 'previously' is an adverb and should not modify 'possibility' which is used as a noun. In the former, adj 'previous' correctly modifies the noun 'possibilty'
am I correct? I have my exam in less than a month and am horrible at SC..