If Walker proves the foregoing facts and offers no other evidence explaining the accident, will his claim survive a motion for directed verdict offered by the defense?
No, because there is no basis for a reasonable inference that Landco was negligent
Yes, because Walker was injured by an artificial condition of the premises while using an adjacent public way. 
Yes, because such an accident does not ordinarily happen in the absence of negligence. 
No, if Landco is in no better position than Walker to explain the accident. 