that, which

'That' is preferred when introducing an essential clause, defined by AP as one that cannot be eliminated without changing the meaning of the sentence. Essential clauses are not set apart by commas. 'Which' is used to introduce nonessential clauses, defined by AP as one that can be eliminated without changing the meaning of the sentence. Nonessential clauses are set off from the rest of the sentence using commas.

Foundation programs that do not directly serve students include FUSION and fiscal sponsorship.

The event, which lasted two hours, was hosted by Kerry.