When two drugs act together to surpass the additive effect of the individual drugs, the interaction is known as
a. cumulative action.
c. additive action.
b. potentiation.
d. synergism.

C additive action because when addicted to one while taking another lead you to being addicted to both 

There are eight major endocrine glands, each with a different function: pituitary gland: the “brain” of the endocrine system; regulates all seven of the other glands and secretes growth hormone.thyroid: regulates a person’s metabolic rate, which is the amount of energy expended daily by a person at rest.thymus: assists in the development of a person’s immune system.adrenal gland: regulates fluid and sodium balance within the body, and secretes epinephrine (“adrenaline”) when the body is under stress, producing the fight-or-flight response.ovaries (in females) and testes (in males): control the development of secondary sex characteristics.pancreatic islets: regulate blood sugar.pineal gland: regulates biorhythms and mood, and stimulates the onset of puberty.