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

With an increase in the number of (A) fuel, approximately four times by 2021, the passenger demand will (B ) passengers fleet expansion and will see (C) airlines add 1,780 planes on domestic routes and 808 on (D) international ones.