Final answer:
Genetic factors and societal pressure are commonly proposed biological causes of eating disorders. Hence the correct answer is option 1
Step-by-step explanation:
One commonly proposed biological cause of eating disorders is genetic factors. Genes are likely involved in the development of eating disorders, as having a close biological relative with an eating disorder significantly increases one's own risk. At a biochemical level, eating disorders may also be caused by the deregulation of neurotransmitters such as serotonin and dopamine, as well as a dysregulation of hormones like leptin and ghrelin.
On the other hand, societal pressure is an important environmental factor that can contribute to the development of eating disorders. Cultural idealization of thinness, especially in females, may play a major role in the development of anorexia nervosa and bulimia nervosa.
Hence the correct answer is option 1