Concept:Scaffolding hypothesis, from Vygotsky’s socio-cultural theory, means that social interaction provides essential support for learning.Explanation:Vygotsky emphasized that learning occurs through social interaction. Scaffolding is a temporary support given to students based on their needs. This support helps bridge learning gaps and expand their abilities. For example, providing sentence starters helps students express ideas easily. Thus, the hypothesis believes that social interaction provides the substantive means by which learning occurs.Answer:Option A: that social interaction provides the substantive means by which learning occurs.