Answer: Census.
Step-by-step explanation:
Given statement:- A research study is done to find the average age of all U.S. factory workers. The researchers asked every factory worker in Ohio what their birth year is.
This research is an example of a census because research in which information is obtained through the responses that all available members of an entire population give to questions.
In other words "Census is an official survey of population in a certain area and records various details about the individuals".
