Final answer:
The actress who had one of the first interracial kisses on TV in 1968's "Plato's Stepchildren" was Nichelle Nichols, who played Lieutenant Uhura in Star Trek.
Step-by-step explanation:
The actress known for one of TV's first interracial kisses in the 1968 episode "Plato's Stepchildren" of the classic series Star Trek is C) Nichelle Nichols. She played the character Lieutenant Uhura and shared this groundbreaking moment with actor William Shatner, who played Captain James T. Kirk. This event is a significant part of television history because it occurred during a time of racial tensions in the United States, making it a bold and important step towards representation on screen.