Paul has begun to use representational thought. He is aware that he has a sister, but it would never occur to him that his sister has a brother and that he is that brother. His mother can still "trick" him into drinking more milk by pouring it into a smaller cup, and telling him he has less to drink. According to Piaget, Paul is at the stage of development.

Pre-operational stage

Explanation:

 The pre-operational stage is one of the type of Piaget's theory and in this stage the children are basically start think at the symbolic development level.

In the pre-operational stage the children basically using the various types of symbols for representing the different the words and it occur at the age of two- seven years.

According to the given question, the Paul is using the pre-operational stage for representing their thoughts. Therefore, Pre-operational stage is the correct answer.      

answer; /// i believe its; // being treated lovingly and predictably by caregivers and learning to trust;

i believe your answer is mountains.