A placebo is a substance that should elicit no positive response in an experimental subject.

A) True

B) False

A) True

Step-by-step explanation:

In an experiment that has the purpose of testing the efficacy of a procedure or drug, comparison is made against the efficacy of a placebo, a procedure or drug that is intended to have no effect whatever.

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Famously, a placebo is often found to be nearly as effective (or even more effective) than the procedure or drug on trial. This effect is known as "the placebo effect."