7.  At one point in the past, a Jewish traveler might have done this to guarantee a safe voyage: 

 A.  Rub his compass against the Kotel 
 B.  Get a blessing from a rabbi at the Kotel 
 C.  Hammer a nail into the Kotel 
 D.  Write the destination on the Kotel

Answer: C   

   Probably frowned upon even in the past, this custom is no longer practiced.