Who was the UN Secretary-General that became the President of Austria?

The correct answer is Kurt Waldheim. He served as the Secretary-General of the United Nations from 1972 to 1981, becoming the first Austrian to hold that position. After his tenure at the UN, Waldheim pursued a career in Austrian politics and was elected as the President of Austria, serving from 1986 to 1992. His unique trajectory from a prominent international diplomatic role to the presidency of his home country is significant and demonstrates the connection between diplomacy and national leadership.

The other individuals listed had noteworthy roles within the UN but did not transition to a presidency in Austria. Ban Ki-moon and Antonio Guterres were both Secretaries-General after Waldheim and have not held political office in Austria. Trygve Lie, the first UN Secretary-General, also did not have any connection to Austrian politics post-UN. This distinction highlights Waldheim's unique path in the context of Austrian history and UN leadership.