A study of 8, 000 randomly chosen adults in a European country found that 75 percent of those who consumed alcohol an average of twice or more per week over a six-month period suffered at least one cold during that period. We can tentatively conclude from this that consuming alcohol tends to increase one' s susceptibility to colds.
The statement 'Eighty percent of those in the study who consumed alcohol three times or more per week suffered colds over the six-month period' would most weaken the argument.