The correct answer is option 1.

In this question, we are matching regional blocks with their respective headquarters.

(A - 4) The Association of Southeast Asian Nations (ASEAN) has its headquarters in Jakarta, hence A matches with 4.

(B - 3) The Commonwealth of Independent States (CIS), which includes a number of Eastern European and Central Asian countries, has its headquarters in Minsk, hence B matches with 3.

(C - 1) The European Union (EU) has its primary headquarters in Brussels, hence C matches with 1.

(D - 2) The Organization of the Petroleum Exporting Countries (OPEC) has its headquarters in Vienna, hence D matches with 2.

The other options (2, 3, and 4) do not correctly match the locations to their respective organizations.