At a district kabaddi academy the trainer observes that players who use the ice bath after practice complain of sore muscles far more often than players who skip it, and he tells the squad that the ice bath is what brings on the soreness. Which of the following, if true, does most to undermine the trainer's inference?

Soreness is the ticket to the ice bath, so the bathers are the sore players gathered together by the physiotherapist and the two groups differ before a single player enters the water. The trainer has taken the reason for the treatment to be its result. The age of the bath, how often the water is changed and the number of practice evenings apply alike to both groups and cannot explain why one group aches and the other does not.