The correct answer is C. Multilaterally.
Explanation
Foreign policy is a term to refer to the relationships that countries establish with others. In this, the countries delegate a group of politicians to represent their country in front of the other countries and establish ties in which different issues such as economy, market, treaties, collaborations or support, among others, are discussed.
Therefore, the best way to implement foreign policy is multilateral, since this is a matter for two or more countries, so the best option is for all countries to participate in the terms and conditions of treaties or agreements that are made. among them. So the correct answer is C. Multilaterally.