The Presidency of the Security Council of the United Nations is rotated among its member states on a monthly basis. This means that each member state gets a chance to hold the presidency for one month throughout the year. During its presidency, a member state has the responsibility of chairing meetings, setting the agenda, and facilitating discussions. The rotation of the presidency ensures that each member state has an equal opportunity to contribute to the decision-making process and influence the Council`s actions. It also reflects the principle of democracy within the United Nations, as no single member state can hold the presidency for an extended period. Therefore, the correct answer is option 1: one month.