The right answer is "Assimilating the counting task to the way she has counted things in the past." According to Jean Piaget's theory of development, assimilation is the process of acquiring new information and adapting it or linking it with existing information. In this case, Irene is not carrying out the assimilation process because she only uses the information she already knows, counting from 1 to 10, and does not understand that she must discriminate according to the type of currency at the time of counting.
I hope my answer can help you.