Choose the sentence that is written correctly.
 A) My friend Tran Nguyen is going, on a summer vacation, with my family. 
 B) My friend Tran Nguyen is going on a summer vacation, with my family. 
 C) My friend, Tran Nguyen, is going on a summer vacation with my family. 
 D) My friend, Tran Nguyen, is going on a summer vacation, with my family.