Final answer:
True, grammar becomes apparent between 18-24 months as children start using two-word phrases, signifying the application of grammatical rules. This illustrates the infants' rapid language development and their inherent ability to learn and apply the structures of language.
Step-by-step explanation:
The statement that grammar becomes obvious between 18-24 months when infants start using two-word combinations is true. By the age of two, toddlers are typically able to use about 50 words and understand at least a couple of hundred more. They begin to form simple sentences, demonstrating an understanding of language rules and grammar. This phase marks a significant milestone in language development, showing the rapid acquisition and application of language skills in young children. It is during this period where gestures start to become part of a more intricate system of communication coupled with verbal expression. This timeframe is also characterized by a remarkable ability for young children to grasp the complex rules of language with relative ease, which is indicative of the biological predisposition to acquire language.
It is evident that grammar becomes more apparent as children expand their vocabulary during these formative months. Using two-word combinations, such as 'more milk' or 'big ball', they communicate not just nouns but also relationships and attributes, applying grammatical structures in rudimentary forms. As they grow, their linguistic capabilities continue to develop, leading to further expansion of vocabulary and complexity in grammar. Moreover, even mistakes at this stage show that children are actively trying to apply grammatical rules, such as an overgeneralization of the plural 's' in English.