Which of the following is a taxable gift?

Elliot sold his house to his son, Jason, for $100,000. Similar houses in Elliot's neighborhood sold for $500,000.

Arianna gave $62,000 to a qualified charitable organization.

Stanley paid $18,000 for his granddaughter's private elementary school tuition. He made the payment directly to the school.

Craig paid $14,000 in hospital bills for his adult daughter, Diane. He paid the hospital directly.