In Their Study Comparing a Placebo to Opioid Drugs, What

Multiple Choice

In their study comparing a placebo to opioid drugs, what did Petrovic and colleagues (2002) conclude?

A) Psychological factors can affect brain function.
B) Drugs should not be prescribed for most painful conditions.
C) Pain is more of a psychological phenomenon than it is physical.
D) Opioid drugs may relieve pain only through the expectation of pain relief.