Gotera: Infants lack the motor ability required to voluntarily produce particular sounds, but produce various babbling sounds randomly. Most children are several years old before they can voluntarily produce most of the vowel and consonant sounds of their language. We can conclude that speech than a process that is abstract or mental.
What this question is testing
Your task
Find the assumption the argument requires in order for its conclusion to hold.
Common trap
Answers that would help the argument but aren't strictly required (sufficient, not necessary).
Winning move
Negate each choice — the right one breaks the argument when negated.
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