Patients who are addicted to cocaine are sometimes using the drug to combat depression. As such,
sometimes addicts are given antidepressant medications to prevent relapse. A three-year study compared the
effects of two such medications, lithium and desipramine, along with a placebo for 72 cocaine users wishing
to break the habit. The patients were put into 3 groups of 24, and given 1 of the 3 treatments at random. This
two-way table illustrates the results.

According to the table, 48 of the addicts relapsed regardless of the treatment given. This number is an
example of a
A. joint frequency.
B. marginal frequency.
C. conditional relative frequency
D. relative frequency