By working in groups, teaching and helping each other, children

The correct option is: are able to reflect on their own thought processes and shift to a higher level of cognitive activity.

Explanation:
When children work collaboratively in groups, teach, and assist one another, they engage in social interaction that promotes higher-order cognitive development. According to Lev Vygotsky's socio-cultural theory of learning, peer interaction and collaborative learning provide scaffolding that enables learners to articulate their reasoning, internalize new concepts, and engage in metacognition (reflecting on their own thinking processes).

This process of group discussion and peer tutoring helps students move beyond basic comprehension to higher levels of cognitive activity, encouraging self-reflection, problem-solving, and a deeper understanding of the subject matter.