A bodybuilder needs to win a regional contest before competing in the national championship. Arnold just won the West Coast regional contest, so he is eligible to compete in the national championship. The last five winners of the West Coast regional contest have all won the national championship. Arnold' s trainer has worked with the last three national champions, and he believes Arnold will win the national championship this year. Thus, Arnold will win the national championship. The argument above is most vulnerable to criticism on the grounds that: ['it draws a hasty generalization based on a small sample size.', 'it confuses a probability with a certainty.', 'it confuses correlation with causation.', 'it confuses a necessary and sufficient condition.']