NATO aims at guaranteeing the freedom and security of its members through political and military means. The rationale of NATO is to provide security for its members. Moreover, NATO works to promote democratic values and enables members to consult and cooperate on defense and security-related issues to solve problems, build trust and, in the long run, prevent conflict. NATO is committed to the peaceful resolution of disputes. If diplomatic efforts fail, it has the military power to undertake crisis-management operations. These are carried out under the collective defense clause of NATO’s founding treaty - Article 5 of the Washington Treaty or under a United-Nations mandate, alone or in cooperation with other countries and international organizations. Therefore, the correct option is C.