Answer:
B. A designed experiment is when a researcher assigns individuals to a certain group, intentionally changing the value of an explanatory variable, and then recording the value of the response variable for each group.
Step-by-step explanation: An experiment is a term used to describe the various procedures or steps put in place or carried out in order to either validate,refute, or support a hypothesis.
A designed experiment is a type of experiment, when the individual conducting the experiment intentionally change certain variables or factors in order to observe or confirm how it affects the other variables or factors.