A survey found that 78% of children with otitis media come from second-hand smoke families. Researchers say that second-hand smoke environments increase unhealthy particles in the air, including nicotine and other toxic substances. Compared with children living in smoke-free environments Children living in second-hand smoke environments are more likely to develop otitis media, so medical experts say that smoking by parents and other families is an important cause of otitis media in children. Which of the following, if true, would weaken the above argument? ['The survey also shows that the rate of smoke-free households is increasing year by year.', 'Research proves that children with secondhand smoke have a higher cure rate for otitis media.', 'Outpatient data shows that otitis media visits to children have decreased by 4.6%.', 'Only 20% of children in this survey are from smoke-free households.']