Final answer:
A census is the research technique that uses every member of the population to obtain data.
Step-by-step explanation:
The research technique that uses every member of the population to obtain data is a census. A census is a method that aims to collect data from every individual in a population to gather comprehensive information. It is commonly used to collect sociological data, such as in the U.S. Census, which gathers demographic data from residents in the United States and its territories.