The correct answer is C. Oslo.
The Nobel Peace Prize is awarded by the Norwegian Nobel Committee in Oslo, Norway. The Nobel Committee is appointed by the Norwegian Parliament. The prize is awarded to the person who in the preceding year “shall have done the most or the best work for fraternity between nations, for the abolition or reduction of standing armies and for the holding and promotion of peace congresses”.
The other options are incorrect. Brussels is the capital of Belgium and the seat of the European Union. Geneva is the second most populous city in Switzerland and the seat of many international organizations, including the United Nations. The Hague is the seat of the International Court of Justice and the International Criminal Court.