kri1311 - It's a classic example of verb sequencing error tested on the GMAT. The sentence describes two related events in past tense; the act of stealing and the act of buying the paintings are the two related past events. As written, the sentence does not clarify the sequence of events, meaning whether the act of stealing took place before the act of buying, or vice-versa. Therefore, the meaning of the sentence is ambiguous.
Corrected versionsThe geographic paintings that
were stolen from the museum
had been bought by the art expert of the museum on the black market.
Buying happened before stealingThe geographic paintings that
had been stolen from the museum
were bought by the art expert of the museum on the black market.
Stealing happened before buying