This answer is unsupported. We don’t know from the study whether the inability to sort objects by color is an effect of an underdeveloped cortex. Rather, we know difficulty in adapting to new rules is an effect of an underdeveloped cortex.

This answer is unsupported. We know that an underdeveloped cortex might prevent someone from adapting to new rules, but we can't say that not a single pre-adolescent child has a developed enough cortex to do so. This is too strong.

This answer is strongly supported. The stimulus suggests that the toddlers behaved the way they did because they were more or less incapable, not because they willfully disregarded the researcher’s instructions.

This answer is unsupported. We don’t know how important of a factor upbringing is for adaptive behavior. Upbringing was not a factor that was part of the researcher’s study.

This answer is unsupported. We don’t know from the study whether the development of a person’s cortex is proportional to this skill. We only know that these two things may be related, not the details of that relationship.