Adrian is performing a research based on co-relational research design which allows him to use various variables and compare the relationships and patterns existing between them.
Explanation:
Co-relational studies include case-control studies and observational studies.
Adrian is researching about the benefits and side effects of drinking tea. To support his theory, he collects evidence based on questionnaires provided to people. He questions about the alertness and happiness level after drinking tea and about risks of getting brain illness with drinking tea. He will co-relate all the results obtained and will conclude his research about the benefits and side effects of drinking tea.