Where was the Hunley built?

Micah is studying child behavior in playgrounds throughout the world. he wants to see how the children react when teachers select the same child to be the first to use each piece of equipment. which approach is micah is using?

Persons who have not yet attained the legal age of consent under the applicable laws in the jurisdiction in which the research was approved.persons who are under 18 years of age.persons who have not yet attained the legal age of consent under the applicable laws in the jurisdiction in which the research will be conducted.persons who are under 21 years of age.

Why can't producers offer a free good for sale?