Answer : 1. "Angola"
Explanation :

The south-western African country Angola has decided to withdraw from the Organization of Petroleum Exporting Countries (OPEC) with effect from January 1, 2024. Angola became a member of OPEC in 2007. Earlier, Ecuador in 2020 and Qatar in 2019 had left this organization. OPEC, an organization of permanent petroleum exporting countries, was established in Baghdad in 1960. Its headquarters is in Vienna, Austria.