Which of the following gifts made by Tristan, age 49, is subject to the generation-skipping transfer tax?

Payment of medical school tuition (directly to the school) of $50,000 for the granddaughter of Joe,

Tristan's best friend. $20,000 to the daughter (age 6) of Tristan's former college roommate.

$40,000 to Todd, the 85-year-old husband of Tristan's sister.

$15,000 to his grandson.

$20,000 to his niece, age 6.