We Can Design a Matched Pairs Experiment When the Data

Short Answer

We can design a matched pairs experiment when the data collected are: $\begin{array}{|l|l|}\hline\text { A. } & \text { observational. } \\\hline \text { B. } & \text { experimental. } \\\hline \text { C. } & \text { controlled. } \\\hline \text { D. } & \text { All these choices are correct. } \\\hline\end{array}$