Final answer:
The author's argument that parenting mistakes can teach children valuable life lessons would be strengthened by adding factual evidence to support the claim. Such evidence could include developmental psychology research or expert opinions demonstrating the benefits of children experiencing their parents' imperfections.
Step-by-step explanation:
The question asks which addition would make the author's argument stronger in the context of a passage about parenting. To strengthen the argument presented in the passage, factual evidence to support the claim would be most beneficial. Factual evidence, such as statistics or findings from reputable studies, would add weight to the author's assertion that making mistakes in parenting can be beneficial for teaching children about life. It would also reinforce the point that striving for perfection is neither necessary nor desirable in parenting.
For example, researching developmental psychology might reveal evidence that children learn resilience and problem-solving through observing and navigating their parents' imperfections. Citing sources like longitudinal studies or expert opinions could also substantiate the claim that children benefit from experiencing a realistic model of dealing with life's challenges rather than a façade of parental perfection.