Of the following situations , which one would most likely begin an exponential growth of the number of greeting cards being ? A) Ann sends 3 greeting cards everyday to a different person . B) Every month, thirty students send greeting cards to their penpals abroad who each agree to send one of their own back . C) Jake sends greeting cards to 3 different friends, who all agree to send greeting cards to three of their friends who agree to do the same . D) Caleb sends 3 greeting cards for every greeting cards that he receives .