The first sentence of the given dialogue of the exhibitor is in present perfect continuous tense and past tense is used in the second sentence.

According to the rules of narration and reporting, present perfect continuous tense is changed into past perfect continuous tense in the indirect speech and past tense is changed into past perfect tense. Also, these in changed into those.

So in indirect speech 'have already been sold' must be changed into 'had already been sold', 'bought' must be 'had bought' and 'these' must be 'those'.

The completed sentence, thus, becomes: The exhibitor apologized saying that both those vases had already been sold and added that a foreigner had bought them only an hour ago.

Thus option D is the correct answer.

Options A,B,C are incorrect as they do not follow the rules of Narration and Reporting.