Sarah stands outside of a grocery store on the west side of town and surveys exiting shoppers about their preference for frozen desserts. what type of sampling technique does sarah's survey represent?

Sarah's survey in which she stands outside of a grocery store and surveys exiting shoppers about their preference for frozen desserts represents a non-probability type of sampling. This sampling includes gathering of samples  in a process that does not give all the individuals in the population equal chances of being selected.
In this case not every individual has the equal chances because Sarah surveys only the shoppers with preferences for frozen desserts.