Final answer:
Brian is demonstrating a lack of theory of mind (TOM) by assuming that Esteban is being greedy without considering other possibilities.
Step-by-step explanation:
Brian is demonstrating a lack of theory of mind (TOM) in assuming that Esteban is being greedy without considering the possibility that his older sister told him to get her a cupcake.
The development of the theory of mind is an important cognitive change that occurs in children between 3 and 5 years old. It allows them to understand that people have thoughts, feelings, and beliefs that are different from their own.
By assuming that Esteban is being greedy, Brian is showing a lack of understanding that Esteban might be carrying out his sister's request.