Step 1: Understanding the Concept:
Lev Vygotsky's sociocultural theory explains self-directed verbalization as a cognitive tool for self-regulation and problem solving.
Step 2: Detailed Explanation:
According to Lev Vygotsky's theory of cognitive development:
Private Speech (egocentric speech) is self-directed speech that young children (ages 2 to 7) use to guide their own behavior, plan actions, and regulate cognitive problem-solving.
Unlike social speech intended for others, private speech is audible self-talk that later internalizes into silent inner speech in older children.
Step 3: Final Answer:
Hence, this is an example of Private speech, corresponding to option (D).