Which of the following is not found in an observational study? A-controlled variable B-manipulated variable C-None of these are found in an observational study. D-control group

C-None of these are found in an observational study

Explanation:

(A.) controlled variables are a part of what's found in a controlled experiment. (B.) manipulated variables are a part of what's found in a controlled experiment. (C.) Answer choice A. or Controlled variables, Answer choice B. or Manipulated variables, and Answer choice D. or Control groups are a part of what's found in a controlled experiment. (D.) Control groups are a part of what's found in a controlled experiment. Therefor this only leaves one answer and that answer is Like I said C-None of these are found in an observational study.

if you look up in the top right corner you'll see your current profile picture, click than click "view profile" you'll be able to change it there.