In the comparative context of Jean Piaget's theory of cognitive development and Lev Vygotsky's theory of socio-cultural development, consider the following statements:

1. 1. Piaget believed that a child's cognitive development precedes their biological maturation and active physical exploration with the environment, while language is merely a by-product of this development.
2. 2. According to Vygotsky, language and thought are initially two independent and separate activities, but around the age of 2 years, language and thought merge within the child, enabling the child to learn to regulate their thinking through 'inner speech'.
3. 3. In Piaget's theory, the child is considered a 'little scientist' who constructs knowledge independently through their own efforts, while in Vygotsky's theory, social interaction and cultural tools are given central importance for the co-construction of knowledge.

Which of the above statement(s) is/are correct?