Concept:Vygotsky’s sociocultural theory emphasises that language is a cultural tool essential for thinking and learning.Explanation:Vygotsky argued that children develop cognitively through social interactions. Language mediates these interactions and helps shape understanding. As a child matures, thought and language become deeply connected. Complex mental processes, like reasoning and problem-solving, rely on language. Therefore, language does not just express thoughts; it actively builds them. This central role of language makes it a key driver of cognitive development. Without language, social learning and higher-order thinking would be limited.Answer:A. plays a central role in cognitive development.