The term "therapeutic index" refers to:

a. Ratio of a drugs lethal dose to its effective dose
b. Amount of drug required to cause a side effect
c. Pharmacokinetics of a drug
d. Efficacy of a drug

a

Rationale: a. The ratio of a drugs lethal dose to its effective dose determines the therapeutic index.
b. Side effects are the undesired effects of a medication.
c. Pharmacokinetics refers to the drugs movement from introduction into the system until system elimination.
d.Efficacy of a drug refers to the potential maximum therapeutic dose a drug can produce