In each of the following sentences, a sentence is given with certain words in bold. Choose the pair/s of such words which need to be interchanged so as to make the sentence grammatically correct and meaningful.

With the U.S. having ended the sanctions (a) purchasing it had given to (b) certain countries, including India, on (c) waiver Iranian oil, from the first week of May, the Iranian economy has come under more (d) pressure.