As per Lev Vygotsky, as children grow, their language develops from _____.

According to Lev Vygotsky's sociocultural theory of cognitive development, language plays a dual role in development: it is both a social tool for communication and a cognitive tool for self-regulation and thinking.

Vygotsky proposed that language development in children progresses through a series of stages:
1. Social Speech (External communication): In the early stages, children use language primarily for social communication with parents, caregivers, and others.
2. Private Speech (Egocentric speech / Thinking out loud): As children grow and face challenging tasks (around ages 3 to 7), they begin to talk to themselves. This "thinking out loud" acts as a self-regulatory mechanism to guide their own behavior, plan actions, and solve problems.
3. Inner Speech (Silent thinking): Eventually, as children mature and internalize this self-directed language (around age 7 or older), private speech becomes quiet and internalized. It transforms into silent "inner speech," which forms the basis for adult thought and self-regulation.

Therefore, as children grow, their language transitions from externalized self-talk or "thinking out loud" to internalized "inner speech".

Thus, the correct option is think out loud to inner speech.