Answer:
primary/observational
Step-by-step explanation:
The primary data may be defined as the data or the information that is collected by the researcher or the experimenter directly from the subjects through any interviews or surveys. It is a first hand information or data collected directly from the source.
In the context, Mary Delany is collecting or gathering the data which is considered as a primary data through an observational methods. The data collected by Mary is primary because she collected the data first hand directly by visiting the local supermarkets from the customers.
And the method of gathering data is observational as she collected data by observing the people or the customers coming to the supermarkets and not by interviewing them.
So, the answer is primary/observational.