Passage Summary: Some parents use 'baby talk' to help their kids learn, but the author argues it's useless because kids who never hear baby talk learn to speak just as well as everyone else.

Conclusion: Using simplified language with babies does not provide them with any additional benefit in learning a language.

Reasoning: Children in families that do not use simplified language master grammatical structures just as quickly and effectively as children in families that do.

Analysis: This is a Necessary Assumption question, so we are looking for a 'missing link' that the argument absolutely requires to function. The author compares two groups of children to conclude that a specific behavior (simplified language) has no effect. For this comparison to be valid, the author must assume that there isn't some other factor in the 'no-baby-talk' families that is making up for the lack of simplified speech. Look for an answer that rules out the possibility that these children are receiving some other form of linguistic boost.