With repeated use of a drug, more of the drug is necessary to ...

[tnt_battle]

With repeated use of a drug, more of the drug is necessary to achieve the same effects. This demonstrates the development of
 
  a. tolerance.
 b. withdrawal.
 c. sensitization.
 d. cross-tolerance.

Question 2

Professor Stevenson and his colleagues observed the motor behavior of children following the administration of a drink with food additives or a drink without the additives. Neither the children nor their observers knew which kind of drink each consumed. This experimental procedure is designed to control for
 
  a. placebo effects.
 b. tolerance.
 c. withdrawal.
 d. the likelihood that some of the children might have attention deficit hyperactivity disorder.

[tkempin]

Answer to Question 1

a

Answer to Question 2

a