Answer:
her belief in an imaginary audience
Step-by-step explanation:
Imaginary audience is a factor that occurs during the increase of self-centeredness of children and adolescents. It occurs when, unrealistically, adolescents consider that others pay as much attention to their appearance and conduct as they themselves.
An example of this can be seen in the question above, where Marsha noticing a stain on her cheek gives up going to school because she believes everyone will notice the stain and judge it for it.