Which of the following would fall into the unknown quadrant in the Johari window?

Kobe has a bad feeling about his upcoming flight, so he decides not to get on the plane, leaving his parents to wonder why he didn't come home.

Hong's friends think that her family is rich, but really she works two jobs to afford the high$-$end clothes she wears.

Sam gets good grades in all of his classes, but he cheats on many of his tests.

Katrina does not realize that five of the boys in her physics class have a crush on her.