Final answer:
The lack of certain grammatical errors in children’s language acquisition suggests the presence of an innate mechanism and internal grammars, providing evidence for an inborn language acquisition device (LAD), making option 'f' correct.
Step-by-step explanation:
The significance that children do not make specific types of grammatical errors suggests that language acquisition is guided by an innate mechanism. This absence of certain errors supports the idea that children do not entirely learn language through explicit instruction, but rather, they possess an underlying biological capability for language development. This capability is in line with Noam Chomsky's proposal of an innate language acquisition device (LAD). Furthermore, the mistakes that children do make, such as overgeneralizations, show that they have an understanding of language rules, pointing to the presence of an internal grammar structure from an early age. Hence, the correct answer to the question would be option 'f', as it correctly identifies both the innate aspects of language acquisition (a) and the internalization of grammatical structures by children (c).