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 where a placebo is administered. this is an example of a(n):

This is an example of an experimental design.

Explanation:

Experimental design in research involves controlling the variables in order to prove the hypothesis. In an experimental design there must be an experimental group, that in this case is the group that received an herbal supplement, and a control group, that was only administered placebo. By having a control group, both groups can be measured and compared at the end of the experimental phase, to measure the influence of the independent variable.