Answer: B) egocentrism
Step-by-step explanation:
Egocentrism is the trait that does not let a person differentiate self and others in a situation.A person might fail in seeing a event or situation from others point-of-view.
According to the question,niece is not able to differentiate doll and self as she thinks doll is a real person.She has not attained concept of toys and does not persist such view point.
Other options are incorrect because animism, socialism and humanitarianism are not the thinking criteria shown by niece.Thus, the correct option is option(B).