A man riding a roller coaster is severely injured when the car he's riding in jumps off the track. He sues the amusement park for negligence. Assuming it is true, which of the following would represent a strong defense against the negligence claim?

• The man undid his seatbelt after the roller coaster started moving.

• The man has seen roller coasters before, and knowingly and voluntarily assumed the risk of participating in a dangerous activity.

• The amusement park has never had an accident like this before.

• The man snuck into the amusement park rather than paying for admission.