Maria works for a marketing firm. She's doing an experimental study where she compares two different clothing stores - Old Army and American Beagle Outfitters - on their customers' satisfaction regarding the customer service they receive while in the store. She has a sample of n=200 people for her study. To 100 people in her sample, she gives a $40 gift certificate to Old Army. For the other 100 people, she gives a $40 gift certificate to American Beagle. She does not let the people in her sample decide which store they want a certificate for, rather, she flips a coin for each one so that each person has an equal chance of getting a certificate to either store. After they go to the store and shop with their gift certificates, she follows up with them, to ask them about their satisfaction with the customer service they received while in the store.

Which statement below is definitely NOT TRUE?

Maria used random assignment.

Maria used random sampling.

Maria used an operational definition.

Maria used the correlational method of research.