Which of the following statements about children and environmental hazards is correct?

The correct answer is B: Children are more susceptible to environmental toxins because of their smaller size. Children have higher exposure to environmental hazards due to their smaller size, higher metabolic rate, and developing organ systems. Their immature immune systems also make them more vulnerable. This makes them more susceptible to the harmful effects of toxins compared to adults. Choice A is incorrect because the incidence of asthma among children has actually been increasing. Choice C is incorrect as susceptibility to cancer is influenced by various factors, not just family history. Choice D is incorrect as the prevalence of autism is a complex issue with multiple factors and not solely linked to environmental toxins.