Which of the following brain mechanisms have been implicated in anorexia?

a) Starvation releases natural pain-reducing opioids producing a high, which reinforces not eating.
b) With puberty, female hormones increase dramatically and damage centers which control eating in the thalamus and pituitary.
c) Excessive exercise depletes the brain of neurotransmitters utilized by areas that regulate hunger or satiation.
d) Stress-released hormones reduce the sensitivity of receptors that detect blood-sugar levels and release hormones that induce hunger.

a