Can anyone help with this please? Thank you

A physician conducts a clinical trial of the effectiveness of running as a treatment for headaches. One group of 4 randomly selected participants undergoes the running

treatment while a control group of 5 randomly selected participants does not. The researchers doing the measurements of headaches are notaware of which participants receive the running treatment and which do not receive it. Identify any problems that are likely to cause confounding and explain how the problems could be avoided.

Identify any problems that are likely to cause confounding. Select all that apply.

A. There is likely to be a placebo effect in this study because the subjects know whether or not they are running.

B.There is no control group.

C. Thegroupsaresosmallthatconfoundingislikelytobeintroducedbytheselection of the group subjects. ofthegroupsubjects.

D. There is likely to be an experimenter effect in this study because the researchers making the headache measurements will influence the participants by knowing which participants run and which participants do not run.

E. If there are differences in the measurements of headaches, there is no way to know if the differences are attributable to thetreatment, running, or the age of theparticipant, young or old.