The correct answer is option 3: Portuguese. The United Nations has six official languages, which are Arabic, Chinese, English, French, Russian, and Spanish. These six languages are used for communication and documentation within the United Nations system. Arabic is one of the official languages due to the significant number of Arabic-speaking countries and the importance of the Arab region in international affairs. Chinese is an official language because of the large population and global impact of China. English and French are the most widely spoken languages internationally and are used as official languages to ensure equal representation. Russian is an official language due to the historical and political influence of Russia. Spanish is an official language because it is widely spoken in many member states. However, Portuguese is not considered an official language of the United Nations.