A Ninety-Year-Old Patient Walked Away from a Nursing Home and Wandered

A ninety-year-old patient walked away from a nursing home and wandered onto some nearby railroad tracks. Once on the tracks, the patient stumbled and sprained his ankle. A few minutes later a train approached. The engineer saw the man on the track and could have stopped, but the train's brakes were defective. As a result, the train hit and killed the man. His family is suing the railroad for negligence in a state that follows the contributory negligence doctrine. In this case,

A) the patient has assumed the risk of wandering onto the railroad tracks.
B) because the patient was contributorily negligent, the railroad has no liability.
C) the train had the last clear chance to avoid the accident, so the patient's contributory negligence does not bar his estate's recovery.
D) the train's striking of the man was an intervening cause, so the railroad company was negligent.