Trained research staff used a structured questionnaire to collect all information for cases and controls. What type of bias does this address?

(1 point) Find an Eulerian walk in the graph above. List the vertices of the Eulerian walk in the order visited. (For your answer, you can enter the letters without spaces, or you can separate the letters by commas.) (You might see an error message on this problem, but please ignore it. This problem has been tested thoroughly and doesn't appear to have any issues.)