A 4-year-old girl has just been removed from her home by social services due to suspicions of abuse and neglect. Severe early life stress can cause changes in functioning of the hypothalamic-pituitary-adrenal (HPA) axis, which in turn can increase risk for the development of future stress-related disorders. Research suggests that modulation at what level may be necessary in order to prevent the changes in HPA functioning that occur with early stress?

a) Hypothalamus
b) Pituitary gland
c) Adrenal cortex
d) Hippocampus