The correct answer is C. Work with other countries through diplomacy.
Step-by-step explanation
Diplomacy is the science that studies everything related to the relations and interests between nations. In addition, diplomacy is a tool to manage International Relations through negotiation, to achieve peace agreements or others that are of interest to both States. According to the previous definition, one of the most used tools to carry out foreign policy is diplomacy. So the correct answer is C. Work with other countries through diplomacy