Son tung is one of the most famous........(Sing) in Viet Nam

Son Tung is one of the most famous singers in Vietnam. In this sentence, the word that is needed to fill in the blank is "singers" because it refers to Son Tung as a person who performs music. The context of the sentence suggests that he is well-known in the field of music in Vietnam, making "singers" the appropriate choice.

In Vietnamese, the complete sentence would be: "Sơn Tùng là một trong những ca sĩ nổi tiếng nhất Việt Nam." The choice of "ca sĩ" parallels the English word "singers," as both terms represent individuals who sing and perform music. The use of the plural form "singers" is also important here because it indicates that he is among many others who are famous, emphasizing his prominence in the music industry.