Manhattan Prep Official Explanation:The room’s appearance could be extraordinary in many ways. Yet, the use of “even Tamika” who is “cleaning her own apartment at increasingly irregular intervals” indicates that the room must be extraordinary in how dirty, or unkempt it has become. “Filthy” would be a good filler.
(A) Inscrutable means “mysterious.” It is not a good match for our filler.
(B) Purified means “uncontaminated” or “untainted.” It is the opposite in meaning to word we are seeking.
(C) Sanitized means “made clean.” It too is the opposite of the word we are seeking.
(D) CORRECT. Squalid means “foul” or “dirty.” This is a nice match for our filler.
(E) Transient means “briefly passing through.” Rooms can be described to have a transient nature if they are set up to be lived in only temporarily, but this term is not a good match the sentence.
(F) CORRECT. Sullied means “dirty” or “soiled” This is a nice match for our filler.
Note that (B) and (C) are a matching pair, but they give the sentence the opposite meaning from the intended one.