Volunteers in a Study Are Assigned Randomly to Groups

Multiple Choice

Volunteers in a study are assigned randomly to groups.Some of the volunteers receive an herbal supplement that is reputed to control nausea,and some of the volunteers are assigned to a control group to which a placebo is administered.This is an example of a(n) :

A) Longitudinal study.
B) Randomized controlled trial (RCT) .
C) Meta-analysis.
D) Appraisal tool.