Four Months After Giving Birth to Her Son, Sarah Tried

Four months after giving birth to her son, Sarah tried to kill the infant by smothering him with a pillow. During the trial, Sarah pleaded not guilty to the attempted murder charge and cited postpartum psychosis as her defense. In the context of trait theories, which of the following is most likely responsible for this form of mental illness in Sarah?

A) Financial changes after childbirth
B) Hormonal changes after childbirth
C) Early childhood experiences
D) Inadequate childcare support